[v2] docs(menu): add imports and complete the example (post merge conflict) (#4742)

* [v2] docs(menu): add imports and complete the example (post merge conflict)

This partially redoes commit cb3305a2fc, as a merge conflict resolution seemed to have accidentally removed a large portion of the changes

- the example was missing imports, which [confused a user](https://stackoverflow.com/q/79827619/3431180), particularly due to the `rt` import alias
  - plus there are a good number of imports too, which this makes explicit
  - also give this file the title `menu.go` for clarity / explicitness, particularly to differentiate from the `NewApp` / `app.go` scaffold
- also handle the error at the end similar to [existing examples](4c464b3092/website/docs/guides/application-development.mdx (L54))

* add changelog entry per PR template

website/docs/reference/menus.mdx

@@ -10,7 +10,21 @@ setting it in the [`Menu`](../reference/options.mdx#menu) application config, or
 
 An example of how to create a menu, using [the `NewApp` scaffold](../guides/application-development.mdx):
 
-```go
+```go title="main.go"
+package main
+
+import (
+    "log"
+    "runtime"
+
+    "github.com/wailsapp/wails/v2"
+    "github.com/wailsapp/wails/v2/pkg/menu"
+    "github.com/wailsapp/wails/v2/pkg/menu/keys"
+    "github.com/wailsapp/wails/v2/pkg/options"
+    rt "github.com/wailsapp/wails/v2/pkg/runtime"
+)
+
+func main() {
     app := NewApp()
 
     AppMenu := menu.NewMenu()
@@ -40,7 +54,10 @@ An example of how to create a menu, using [the `NewApp` scaffold](../guides/appl
             app,
         },
     })
-    // ...
+    if err != nil {
+        log.Fatal(err)
+    }
+}
 ```
 
 It is also possible to dynamically update the menu, by updating the menu struct and calling

website/src/pages/changelog.mdx

@@ -16,7 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
-- Updated menu reference docs with complete imports by @agilgur5 in [#4727](https://github.com/wailsapp/wails/pull/4727)
+- Updated menu reference docs with complete imports by @agilgur5 in [#4727](https://github.com/wailsapp/wails/pull/4727) and [#4742](https://github.com/wailsapp/wails/pull/4742)
 - Fixed menu reference syntax by @agilgur5 in [#4726](https://github.com/wailsapp/wails/pull/4726)
 - Fixed indentation in Application Development guide by @agilgur5 in [#4730](https://github.com/wailsapp/wails/pull/4730)
 - Updated Application Development guide to show imports in the `app.go` snippets by @agilgur5 in [#4731](https://github.com/wailsapp/wails/pull/4731)