Maintainer docs for patch merging

["Tobin C. Harding" <me@tobin.cc>]

Hi,

Recently we started a maintainer book (merged into Jonathan's docs-next
branch).

Would any current maintainers please be willing to explain how they go
about generating the automated emails one often receives when a patch
[set] is applied.

This may also be related to tree/branch management for maintainers
kernel.org shows some people like to use multiple trees and some use
branches? 

If deemed relevant we could add a section to the new book (and I'd also
like to know how to do it for my own tree please so I can copy ;)

I have CC'd Greg and Andrew because they seem to have a system in place
for this.

No rush on this, I know Christmas is soon.

thanks,
Tobin.