[ENHANCEMENT] Fill Contribution Page

[anjelicamajewski]

Is your feature request related to a problem? Please describe.
https://docs.librephotos.com/docs/development/contribution/ is a blank page at the moment

Describe the enhancement you'd like
I'd like to add to the page to add instructions on how to contribute.

Describe alternatives you've considered
Add pointers on where to go for contribution instructions.

Additional context
I'm not exactly sure how to contribute to the docs because there is no doc explaining how to do so.