docs(gnokey): add more info on vm/qfile (#2770)

<!-- please provide a detailed description of the changes made in this
pull request. -->

## Description

This PR adds more info for the `vm/qfile` query.

<details><summary>Contributors' checklist...</summary>

- [x] Added new tests, or not needed, or not feasible
- [x] Provided an example (e.g. screenshot) to aid review or the PR is
self-explanatory
- [x] Updated the official documentation or not needed
- [x] No breaking changes were made, or a `BREAKING CHANGE: xxx` message
was included in the description
- [x] Added references to related issues and PRs
- [x] Provided any useful hints for running manual tests
- [x] Added new benchmarks to [generated
graphs](https://gnoland.github.io/benchmarks), if any. More info
[here](https://github.com/gnolang/gno/blob/master/.benchmarks/README.md).
</details>

docs/gno-tooling/cli/gnokey/querying-a-network.md

@@ -23,7 +23,7 @@ Below is a list of queries a user can make with `gnokey`:
 - `auth/accounts/{ADDRESS}` - returns information about an account
 - `bank/balances/{ADDRESS}` - returns balances of an account
 - `vm/qfuncs` - returns the exported functions for a given pkgpath
-- `vm/qfile` - returns the list of files for a given pkgpath
+- `vm/qfile` - returns package contents for a given pkgpath
 - `vm/qeval` - evaluates an expression in read-only mode on and returns the results
 - `vm/qrender` - shorthand for evaluating `vm/qeval Render("")` for a given pkgpath
 
@@ -124,14 +124,16 @@ data: [
 
 ## `vm/qfile`
 
-With the `vm/qfile` query, we can fetch files found on a specific package path.
-To specify the path we want to query, we can use the `-data` flag:
+With the `vm/qfile` query, we can fetch files and their content found on a 
+specific package path. To specify the path we want to query, we can use the 
+`-data` flag:
 
 ```bash
 gnokey query vm/qfile -data "gno.land/r/demo/wugnot" -remote https://rpc.gno.land:443
 ```
 
-The output is a list of all files found within the `wugnot` realm:
+If the `-data` field contains only the package path, the output is a list of all
+files found within the `wugnot` realm:
 
 ```bash
 height: 0
@@ -140,6 +142,40 @@ wugnot.gno
 z0_filetest.gno
 ```
 
+If the `-data` field also specifies a file name after the path, the source code
+of the file will be retrieved:
+
+```bash
+gnokey query vm/qfile -data "gno.land/r/demo/wugnot/wugnot.gno" -remote https://rpc.gno.land:443
+```
+
+Output: 
+```bash
+height: 0
+data: package wugnot
+
+import (
+        "std"
+        "strings"
+
+        "gno.land/p/demo/grc/grc20"
+        "gno.land/p/demo/ufmt"
+        pusers "gno.land/p/demo/users"
+        "gno.land/r/demo/users"
+)
+
+var (
+        banker *grc20.Banker = grc20.NewBanker("wrapped GNOT", "wugnot", 0)
+        Token                = banker.Token()
+)
+
+const (
+        ugnotMinDeposit  uint64 = 1000
+        wugnotMinDeposit uint64 = 1
+)
+...
+```
+
 ## `vm/qeval`
 
 `vm/qeval` allows us to evaluate a call to an exported function without using gas,