docs template

[alisterburt]

Hey @LorenzLamm

So great to see you pushing this again - in this PR you have all that you need to work on documentation, I'm using mkdocs-material

basics:

• pip install mkdocs-material
• write markdown in docs folder
• if you add images, put them in comments on a github issue and reference the URL of that uploaded image
• mkdocs serve in the repo root for local preview
• there is a github action for deployment to GitHub pages which will make the site available at teamtomo.org/membrain-seg

Please feel free to merge this PR and iterate, editing an existing thing is always much easier than starting from scratch :)