"?" instead of "&" in request examples

Attempt to update google-protobuf for migration-paths

Because the one we were using aren't compatible with
Ruby 2.5.3, and it'll be troublesome to switch Ruby.
Upgrading google-protobuf will be much easier.

All of them will need to be updated for Ruby 2.5.3

We remove oj because we don't really need it and it
doesn't compile on 2.5.3 with that version.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/41825

This updates the documentation for adding EE specific features to
clarify that `prepend` should be on the last line, and how to deal with
code that depends on class methods redefined in EE.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/53919

Adds a detailed explanation on what the user can expect to see
in case a git pull or push operation times out on their local machines

This recently changed on the Gitaly side, but now spotted this in the
docs for the next release. Updated to be more precise, and to signal
users should not want control over this specific hook location.

Signed-off-by: Rémy Coutable <remy@rymai.me>

This prevents some of the abusive behaviors, of someone putting 100000 and creating out of memory condition easily

Also corrects capitalisation of Git.