dirstate-v2: Document flags/mode/size/mtime fields of tree nodes
This file format modification was previously left incomplete because of
planned upcoming changes. Not all of these changes have been made yet,
but documenting what exists today will help talking more widely about it.
Differential Revision: https://phab.mercurial-scm.org/D11625
$ LANG=nonexistent LC_ALL=nonexistent LANGUAGE=nonexistent hg version -q
Mercurial Distributed SCM (version *) (glob)