Merge branch 'rj/log-decorate-auto'

We forgot to add "git log --decorate=auto" to documentation when we
added the feature back in v2.1.0 timeframe.

* rj/log-decorate-auto:
  log: document the --decorate=auto option

Author: gitster

Documentation/config.txt

@@ -1956,7 +1956,10 @@ log.decorate::
 	command. If 'short' is specified, the ref name prefixes 'refs/heads/',
 	'refs/tags/' and 'refs/remotes/' will not be printed. If 'full' is
 	specified, the full ref name (including prefix) will be printed.
-	This is the same as the log commands '--decorate' option.
+	If 'auto' is specified, then if the output is going to a terminal,
+	the ref names are shown as if 'short' were given, otherwise no ref
+	names are shown. This is the same as the '--decorate' option
+	of the `git log`.
 
 log.follow::
 	If `true`, `git log` will act as if the `--follow` option was used when

Documentation/git-log.txt

@@ -29,12 +29,14 @@ OPTIONS
 	(works only for a single file).
 
 --no-decorate::
---decorate[=short|full|no]::
+--decorate[=short|full|auto|no]::
 	Print out the ref names of any commits that are shown. If 'short' is
 	specified, the ref name prefixes 'refs/heads/', 'refs/tags/' and
 	'refs/remotes/' will not be printed. If 'full' is specified, the
-	full ref name (including prefix) will be printed. The default option
-	is 'short'.
+	full ref name (including prefix) will be printed. If 'auto' is
+	specified, then if the output is going to a terminal, the ref names
+	are shown as if 'short' were given, otherwise no ref names are
+	shown. The default option is 'short'.
 
 --source::
 	Print out the ref name given on the command line by which each