docs: link unlinked type references in API documentation (#49651)

docs: add missing type links in menu.md and shared-texture.md

docs/api/menu.md

@@ -123,7 +123,7 @@ Appends the `menuItem` to the menu.
 
 - `id` string
 
-Returns `MenuItem | null` the item with the specified `id`
+Returns [`MenuItem | null`](menu-item.md) - the item with the specified `id`
 
 #### `menu.insert(pos, menuItem)`
 

docs/api/shared-texture.md

@@ -21,7 +21,7 @@ Imports the shared texture from the given options.
 > [!NOTE]
 > This method is only available in the main process.
 
-Returns `SharedTextureImported` - The imported shared texture.
+Returns [`SharedTextureImported`](structures/shared-texture-imported.md) - The imported shared texture.
 
 ### `sharedTexture.sendSharedTexture(options, ...args)` _Experimental_