[$] Toward a kernel maintainer's guide

"Who's on Team Xmas Tree?" asked Dan Williams at the beginning of his talkin the Kernel Summit track of the 2018Linux Plumbers Conference. Hewas referring to a rule for the ordering of local variable declarationswithin functions that is enforced by a minority of kernel subsystemmaintainers - one of many examples of "local customs" that can surprisedevelopers when they submit patches to subsystems where they are notaccustomed to working. Documenting these varying practices is a small partof Williams's project to create a kernel maintainer's manual, but it seemsto be where the effort is likely to start.