config: expand hgrc %include paths

rename: make --after work if source is already in R state I routinely want to use `hg addrem` and then fix up missed renames manually using `hg mv -A`. This patch allows me to record such renames from a source in state R to a target in state A.

Merge with stable

doc: clarify that sections can be split

doc: clarify that keys can be overridden

commands: document --new-branch flag for push