Block user functionality is undocumented

Related to: https://gitlab.com/gitlab-org/gitlab-ce/issues/45552

Summary

Whilst writing documentation for abuse reports I realised I didn't know exactly what happens to a blocked user. I can assume that they can no longer access the instance, but all of their data and references are retained. But I couldn't be sure without documentation.

Steps to reproduce

https://www.google.com/search?q=block+site:docs.gitlab.com&ei=N6HYWuOvF6fPgAaVh5-YCQ&start=0&sa=N&biw=2560&bih=1305

What is the expected correct behaviour?

We should have documentation explaining how to block and user and what happens when a user is blocked.

Possible fixes

Write documentation explaining how to block and user and what happens when a user is blocked.

Edited by Luke Bennett