Broken link to mamba installation page

[weiji14]

Link to the mamba installation page pointing to https://mamba.readthedocs.io/en/latest/mamba-installation.html is broken here:

sarxarray/docs/setup.md

Line 31 in 3a11cd0

We strongly recommend installing separately from your default Python environment. E.g. you can use environment manager (e.g. [mamba](https://mamba.readthedocs.io/en/latest/mamba-installation.html)) to create a separate environment.

Should point to https://mamba.readthedocs.io/en/latest/installation/mamba-installation.html instead.

Found using https://lychee.cli.rs/.

[rogerkuou]

Thanks @weiji14 ! This issue will be fixed by #100 . Feel free to leave thoughts/comments!

Also thanks for suggesting lychee! I added it to #101 for consideration of tsch stack update.