Add a menu entry for documentation

[Xpirix]

• [ ] Create a menu called "Documentation"
• [ ] Create a submenu called "Publish a plugin" and link the publish page docs to it
• [ ] Render the publish page docs as a static page instead of getting it from the DB to facilitate its maintenance
• [ ] Create a submenu called "Manage a plugin"
• [ ] Include the documentation about reviving a deprecated plugin to the Manage a plugin menu
• [ ] Include other useful documentation related to the Plugins Website (Add versions, Rename a plugin, Token Usage, Plugin statistics...)