Clarify installation instructions in documentation, not just README

[PeterDaveHello]

Currently, neither the README nor the documentation site clearly state how to install urlwatch (such as via pip). While README serves more as a project overview, installation steps are best placed in the documentation itself, ideally in the Quick Start section or as a new dedicated Installation section.

Adding clear installation instructions in the docs would make onboarding easier for new users and help avoid confusion.

I'm happy to contribute this improvement if helpful. This suggestion aims to keep documentation organized and user-friendly, and to make urlwatch even more approachable for everyone.

Open to any suggestions or discussion on how best to implement this.

[Jamstah]

I like the idea. I would recommend pipx for any platform that doesn't have a package already.

[Jamstah]

Fyi there are some instructions here too: https://thp.io/2008/urlwatch/

[thp]

Feel free to propose a PR :+1:

[PeterDaveHello]

PR #856 sent! @thp @Jamstah please feel free to take a look! It's just a basic version that should be helpful enough. More enhancement can be made in the future 😄