docs: added docs on 08-wasm options api (cosmos#5398)

* docs: added docs on options api

* review comments

* review comment

* docs: added docs on stargate querier

* docs: improved style

* docs: using permalink

---------

Co-authored-by: Carlos Rodriguez <carlos@interchain.io>

docs/docs/03-light-clients/04-wasm/03-integration.md

@@ -63,18 +63,13 @@ func NewSimApp(
   // This is the recommended approach when the chain
   // also uses `x/wasm`, and then the Wasm VM instance
   // can be shared.
-  // This sample code uses also an implementation of the 
-  // wasmvm.Querier interface (querier). If nil is passed
-  // instead, then a default querier will be used that
-  // returns an error for all query types.
-  // See the section below for more information.
   app.WasmClientKeeper = wasmkeeper.NewKeeperWithVM(
     appCodec,
     runtime.NewKVStoreService(keys[wasmtypes.StoreKey]),
     app.IBCKeeper.ClientKeeper,
     authtypes.NewModuleAddress(govtypes.ModuleName).String(),
     wasmVM,
-    querier,
+    app.GRPCQueryRouter(),
   )  
   app.ModuleManager = module.NewManager(
     // SDK app modules
@@ -130,7 +125,7 @@ func NewSimApp(
 
 ## Keeper instantiation
 
-When it comes to instantiating `08-wasm`'s keeper there are two recommended ways of doing it. Choosing one or the other will depend on whether the chain already integrates [`x/wasm`](https://github.com/CosmWasm/wasmd/tree/main/x/wasm) or not. Both available constructor functions accept a querier parameter that should implement the [`Querier` interface of `wasmvm`](https://github.com/CosmWasm/wasmvm/blob/v1.5.0/types/queries.go#L37). If `nil` is provided, then a default querier implementation is used that returns error for any query type.
+When it comes to instantiating `08-wasm`'s keeper there are two recommended ways of doing it. Choosing one or the other will depend on whether the chain already integrates [`x/wasm`](https://github.com/CosmWasm/wasmd/tree/main/x/wasm) or not.
 
 ### If `x/wasm` is present
 
@@ -199,17 +194,13 @@ app.WasmKeeper = wasmkeeper.NewKeeper(
   wasmOpts...,
 )
 
-// This sample code uses also an implementation of the 
-// wasmvm.Querier interface (querier). If nil is passed
-// instead, then a default querier will be used that
-// returns an error for all query types.
 app.WasmClientKeeper = wasmkeeper.NewKeeperWithVM(
   appCodec,
   runtime.NewKVStoreService(keys[wasmtypes.StoreKey]),
   app.IBCKeeper.ClientKeeper,
   authtypes.NewModuleAddress(govtypes.ModuleName).String(),
   wasmer, // pass the Wasm VM instance to `08-wasm` keeper constructor
-  querier,
+  app.GRPCQueryRouter(),
 )
 ...
 ```
@@ -250,12 +241,70 @@ app.WasmClientKeeper = wasmkeeper.NewKeeperWithConfig(
   app.IBCKeeper.ClientKeeper, 
   authtypes.NewModuleAddress(govtypes.ModuleName).String(),
   wasmConfig,
-  querier
+  app.GRPCQueryRouter(),
 )
 ```
 
 Check out also the [`WasmConfig` type definition](https://github.com/cosmos/ibc-go/blob/c95c22f45cb217d27aca2665af9ac60b0d2f3a0c/modules/light-clients/08-wasm/types/config.go#L7-L20) for more information on each of the configurable parameters. Some parameters allow node-level configurations. There is additionally the function [`DefaultWasmConfig`](https://github.com/cosmos/ibc-go/blob/6d8cee53a72524b7cf396d65f6c19fed45803321/modules/light-clients/08-wasm/types/config.go#L30) available that returns a configuration with the default values.
 
+### Options
+
+The `08-wasm` module comes with an options API inspired by the one in `x/wasm`.
+Currently the only option available is the `WithQueryPlugins` option, which allows registration of custom query plugins for the `08-wasm` module. The use of this API is optional and it is only required if the chain wants to register custom query plugins for the `08-wasm` module.
+
+#### `WithQueryPlugins`
+
+By default, the `08-wasm` module does not support any queries. However, it is possible to register custom query plugins for [`QueryRequest::Custom`](https://github.com/CosmWasm/cosmwasm/blob/v1.5.0/packages/std/src/query/mod.rs#L45) and [`QueryRequest::Stargate`](https://github.com/CosmWasm/cosmwasm/blob/v1.5.0/packages/std/src/query/mod.rs#L54-L61).
+
+Assuming that the keeper is not yet instantiated, the following sample code shows how to register query plugins for the `08-wasm` module.
+
+We first construct a [`QueryPlugins`](https://github.com/cosmos/ibc-go/blob/57fcdb9a9a9db9b206f7df2f955866dc4e10fef4/modules/light-clients/08-wasm/types/querier.go#L78-L87) object with the desired query plugins:
+
+```go
+queryPlugins := ibcwasmtypes.QueryPlugins {
+  Custom: MyCustomQueryPlugin(),
+  // `myAcceptList` is a `[]string` containing the list of gRPC query paths that the chain wants to allow for the `08-wasm` module to query.
+  // These queries must be registered in the chain's gRPC query router, be deterministic, and track their gas usage.
+  // The `AcceptListStargateQuerier` function will return a query plugin that will only allow queries for the paths in the `myAcceptList`.
+  // The query responses are encoded in protobuf unlike the implementation in `x/wasm`.
+  Stargate: ibcwasmtypes.AcceptListStargateQuerier(myAcceptList),
+}
+```
+
+You may leave any of the fields in the `QueryPlugins` object as `nil` if you do not want to register a query plugin for that query type.
+
+Then, we pass the `QueryPlugins` object to the `WithQueryPlugins` option:
+
+```go
+querierOption := ibcwasmtypes.WithQueryPlugins(queryPlugins)
+```
+
+Finally, we pass the option to the `NewKeeperWithConfig` or `NewKeeperWithVM` constructor function during [Keeper instantiation](#keeper-instantiation):
+
+```diff
+app.WasmClientKeeper = wasmkeeper.NewKeeperWithConfig(
+  appCodec,
+  runtime.NewKVStoreService(keys[wasmtypes.StoreKey]),
+  app.IBCKeeper.ClientKeeper, 
+  authtypes.NewModuleAddress(govtypes.ModuleName).String(),
+  wasmConfig,
+  app.GRPCQueryRouter(),
++ querierOption,
+)
+```
+
+```diff
+app.WasmClientKeeper = wasmkeeper.NewKeeperWithVM(
+  appCodec,
+  runtime.NewKVStoreService(keys[wasmtypes.StoreKey]),
+  app.IBCKeeper.ClientKeeper,
+  authtypes.NewModuleAddress(govtypes.ModuleName).String(),
+  wasmer, // pass the Wasm VM instance to `08-wasm` keeper constructor
+  app.GRPCQueryRouter(),
++ querierOption,
+)
+```
+
 ## Updating `AllowedClients`
 
 In order to use the `08-wasm` module chains must update the [`AllowedClients` parameter in the 02-client submodule](https://github.com/cosmos/ibc-go/blob/main/proto/ibc/core/client/v1/client.proto#L103) of core IBC. This can be configured directly in the application upgrade handler with the sample code below:
@@ -270,7 +319,7 @@ Or alternatively the parameter can be updated via a governance proposal (see at
 
 ## Adding snapshot support
 
-In order to use the `08-wasm` module chains are required to register the `WasmSnapshotter` extension in the snapshot manager. This snapshotter takes care of persisting the external state, in the form of contract code, of the Wasm VM instance to disk when the chain is snapshotted. [This code](https://github.com/cosmos/ibc-go/blob/2bd29c08fd1fe50b461fc33a25735aa792dc896e/modules/light-clients/08-wasm/testing/simapp/app.go#L768-L776) should be placed in `NewSimApp` function in `app.go`:
+In order to use the `08-wasm` module chains are required to register the `WasmSnapshotter` extension in the snapshot manager. This snapshotter takes care of persisting the external state, in the form of contract code, of the Wasm VM instance to disk when the chain is snapshotted. [This code](https://github.com/cosmos/ibc-go/blob/2bd29c08fd1fe50b461fc33a25735aa792dc896e/modules/light-clients/08-wasm/testing/simapp/app.go#L768-L776) should be placed in `NewSimApp` function in `app.go`.
 
 ## Pin byte codes at start
 

docs/docs/03-light-clients/04-wasm/05-governance.md

@@ -33,7 +33,7 @@ app.WasmClientKeeper = wasmkeeper.NewKeeperWithVM(
   app.IBCKeeper.ClientKeeper,
  	authtypes.NewModuleAddress(govtypes.ModuleName).String(), // authority
   wasmVM,
-  querier,
+  app.GRPCQueryRouter(),
 )
 ```