Documentation: rerere.enabled is the primary way to configure rerere

The wording seems to suggest that creating the directory is needed and the
setting of rerere.enabled is only for disabling the feature by setting it
to 'false'. But the configuration is meant to be the primary control and
setting it to 'true' will enable it; the rr-cache directory will be
created as necessary and the user does not have to create it.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -1700,10 +1700,10 @@ rerere.autoupdate::
 
 rerere.enabled::
 	Activate recording of resolved conflicts, so that identical
-	conflict hunks can be resolved automatically, should they
+	conflict hunks can be resolved automatically, should they be
-	be encountered again.  linkgit:git-rerere[1] command is by
+	encountered again.  By default, linkgit:git-rerere[1] is
-	default enabled if you create `rr-cache` directory under
+	enabled if there is an `rr-cache` directory under the
-	`$GIT_DIR`, but can be disabled by setting this option to false.
+	`$GIT_DIR`.
 
 sendemail.identity::
 	A configuration identity. When given, causes values in the