Update migration documentation for *_with_env(…) functions

docs/migration_to_3.0.0.md

@@ -20,8 +20,13 @@ This version introduces the following changes to make the Wasmer API more ergono
 
 1. `ImportsObject` and the traits `Resolver`, `NamedResolver`, etc have been removed and replaced with a single simple type `Imports`. This reduces the complexity of setting up an `Instance`. The helper macro `imports!` can still be used.
 2. The `Store` will keep track of all memory and functions used, removing old tracking and Weak/Strong pointer usage. Every function and memory that can be defined is associated to a specific `Store`, and cannot be mixed with another `Store`
-3. `WasmerEnv` and associated traits and macro have been removed. To use a function environment, you will need to create a `FunctionEnv` object and  pass it along when you construct the function. The environment can be retrieved from the first argument of the function. All functions now takes a mandatory first argument that is of type `FunctionEnvMut<'_, _>`, with `_` being either nothing `()` or the defined environment type. The function creation `XXX_with_env(...)` don't exist anymore, simply use `Function::new(...)` or `Function::native_new(...)` with the correct `FunctionEnv<_>` type. Because the `WasmerEnv` and all helpers don't exists anymore, you have to import memory yourself, there isn't any per instance initialisation automatically done anymore. It's especially important in wasi use with `WasiEnv`. `Env` can be accessed from a `FunctionEnvMut<'_, WasiEnv>` using `FunctionEnvMut::data()` or `FunctionEnvMut::data_mut()`.
-4. The `Engine`s API has been simplified, Instead of the user choosing and setting up an engine explicitly, everything now uses a single engine. All functionalities of the `universal`, `staticlib` and `dylib` engines should be available in this new engine unless explicitly stated as unsupported.
+3. `NativeFunc` has been renamed to `TypedFunction`, accordingly the following functions have been renamed:
+   * `Function::native(…)` → `Function::typed(…)`
+   * `Function::new_native(…)` → `Function::new_typed(…)`
+   * `Function::new_native_with_env(…)` → `Function::new_typed_with_env(…)`
+   The previous variants still exist in order to support the migration, but they have been deprecated.
+4. `WasmerEnv` and associated traits and macro have been removed. To use a function environment, you will need to create a `FunctionEnv` object and pass it along when you construct the function. For convenience, these functions also exist in a variant without the environment for simpler use cases that don't need it. For the variants with the environment, it can be retrieved from the first argument of the function. Because the `WasmerEnv` and all helpers don't exists anymore, you have to import memory yourself, there isn't any per instance initialisation automatically done anymore. It's especially important in wasi use with `WasiEnv`. `Env` can be accessed from a `FunctionEnvMut<'_, WasiEnv>` using `FunctionEnvMut::data()` or `FunctionEnvMut::data_mut()`.
+5. The `Engine`s API has been simplified, Instead of the user choosing and setting up an engine explicitly, everything now uses a single engine. All functionalities of the `universal`, `staticlib` and `dylib` engines should be available in this new engine unless explicitly stated as unsupported.
 
 ## How to use Wasmer 3.0.0