[Proposal] Improve the docs

[maheshj01]

This issue tracks a request to improve the documentation for this package. This issue will be marked as closed when all the below conditions are met.

• [x] Publish docs using docs.page
• [ ] Include examples for different use cases.
• [ ] Keep readme.md clear and concise.
• [x] Add a link to detailed documentation in the readme.md.
• [ ] Update the medium blogpost as per the current state of the package.
• [x] Add a showcase section showing the apps that use NavbarRouter.
• [ ] Add a link to edit the docs

[maheshj01]

Things to include in the docs

• [x] Add an index change Listener
• [x] Document and provide samples of how routes are pushed on top of each tab and flutter's Navigator stack based on the discussion in this Issue #21.
• [ ] Medium post specify using BottomNavigationbar hides the navbar when pushing routes.
• [x] Update the screenshots in readme with the new sample app (uses material 3)
• [ ] Add navigation animation to docs.

[maheshj01]

The docs are available at https://docs.page/maheshmnj/navbar_router contribute here: https://github.com/maheshmnj/navbar_router/edit/main/docs/index.mdx

[maheshj01]

The decoration properties are now being loaded from constants: https://github.com/maheshmnj/docs/blob/main/src/constants.js on navbar_router/types