Code clean-up.
* ma/parse-maybe-bool:
parse_decoration_style: drop unused argument `var`
treewide: deprecate git_config_maybe_bool, use git_parse_maybe_bool
config: make git_{config,parse}_maybe_bool equivalent
config: introduce git_parse_maybe_bool_text
t5334: document that git push --signed=1 does not work
Doc/git-{push,send-pack}: correct --sign= to --signed=