Make nimble documentation easier to find
Add a link to https://nim-lang.github.io/nimble/index.html to:

1. - [ ] https://nim-lang.org/documentation.html (section "Search" or "Other")
1. - [ ] https://nim-lang.org/docs/tools.html
1. - [x] In the Github repo description of https://github.com/nim-lang/nimble
1. - [ ] In the readme of https://github.com/nim-lang/packages/
1. - [ ] In the header or footer of https://nimble.directory/ 

![grafik](https://github.com/user-attachments/assets/8a891ca8-2fc8-4b62-a262-4ee223a03fb1)

Example of how it is done on PyPI.org:

![grafik](https://github.com/user-attachments/assets/0dfcf7ed-39e0-41c0-8029-552abfb5746a)
