Merge pull request #18076 from joscollin/wip-contributor-list-maintenance-guide

mailmap: Fixed maintenance guide URL

Reviewed-by: Abhishek Lekshmanan <abhishek.lekshmanan@gmail.com>

diff --cc .githubmap
Simple merge

diff --cc .mailmap
Simple merge

diff --cc .organizationmap
Simple merge

diff --cc .peoplemap
Simple merge