Add docs for build your own image feature

[j08lue]

We now have a working feature on https://hub.openveda.cloud/ for users to build their own image for JupyterLab off of a repository that conforms to certain lightweight standards (Binder).

We need to document this feature and its limitations

Acceptance criteria

• Added docs about when to use this feature, how, and when not

[wildintellect]

Questions to answer:

• What do you need to fill in the boxes?
• How does it know when to build again? only when you change the env.yaml or on every commit? most people will set a branch and always use that never tagging or specifying specific commits.
• What needs to exist in your repo to customize the build (does this currently only support conda customization?)
• What upstream docs like repo2docker should we reference?

[wildintellect]

Things we've noticed:

• It's case sensitive github.com/MAAP-Project/sar2-d2 and github.com/maap-project/sar2-d2 both built. 😱

Where's the source code for this feature @yuvipanda?

[yuvipanda]

What needs to exist in your repo to customize the build (does this currently only support conda customization?)

https://repo2docker.readthedocs.io/en/latest/config_files.html has a list of files that are interpreted automatically. If you have a Dockerfile it ignores all other files and only uses that.