improve git-diff documentation and A...B handling #1

ddevault wants to merge 3 commits from forgeperf into master

3 Commits (master)

Author SHA1 Message Date
Chris Torek 582b12190e Documentation: usage for diff combined commits 2 years ago
Chris Torek 80151fec44 git diff: improve range handling 2 years ago
Chris Torek 36cca09f38 t/t3430: avoid undefined git diff behavior 2 years ago