feat(window-menu): add docs for the `menu`

[RSS1102]

Description

• What does this PR change? Give us a brief description.

I would like to summarize and explain the use of menu

The following problems will be solved：

• rust
• [x] one level menu, two (multiple) levels of settings.
• [x] custom menu items.
• [x] menu event handling.
• [x] reset (how to change menu status/language/etc.)
• [x] Menu Event
• [ ] accelerator
• JavaScript
• [x] one level menu, two (multiple) levels of settings.
• [ ] custom menu items.
• [ ] menu event handling.
• [ ] reset (how to change menu status/language/etc.)
• [ ] Menu Event
• [ ] accelerator

I will refer to：

• https://github.com/tauri-apps/tauri-docs/blob/7cf5fbb901e67680e20809c7ee983f863698fcf6/src/content/docs/start/migrate/from-tauri-1.mdx#migrate-to-menu-module
• https://github.com/tauri-apps/tauri-docs/blob/7cf5fbb901e67680e20809c7ee983f863698fcf6/src/content/docs/plugin/system-tray.mdx#add-a-menu
• https://v1.tauri.app/v1/guides/features/menu If nothing goes wrong, it will be completed within two weeks, after I have tested the code of each function (Rust has been tested, but JavaScript has not yet been tested)

If anyone has any questions about the use of menu, please add them below. I will try my best to enrich the documentation on using menu.