Write end user documentation (on 2i2c-org/docs repo) on specifying your own image

[yuvipanda]

This is focused on an end user, and designed to be a link given by community champions to their users.

Example from @jbusecke at leap-stc/leap-stc.github.io#80.

[consideRatio]

This is focused on an end user, and designed to be a link given by community champions to their users.

I appreciate this specification, I think it would be good if we are very mindful about the target audience for each piece of documentation we write. I think specificity that can help us maintain that specific doc page over time and the structure including it a lot easier.