Merge branch 'bs/doc-blame-color-lines'

The "--color-lines" and "--color-by-age" options of "git blame"
have been missing, which are now documented.

* bs/doc-blame-color-lines:
  blame: document --color-* options
  blame: describe default output format

diff --cc Documentation/blame-options.txt
Simple merge

diff --cc Documentation/config/color.txt
Simple merge

diff --cc Documentation/git-blame.txt
Simple merge