config: add markup to core.logAllRefUpdates doc

Signed-off-by: Cornelius Weig <cornelius.weig@tngtech.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: Cornelius Weig

Documentation/config.txt

@@ -517,10 +517,10 @@ core.logAllRefUpdates::
 	"`$GIT_DIR/logs/<ref>`", by appending the new and old
 	SHA-1, the date/time and the reason of the update, but
 	only when the file exists.  If this configuration
-	variable is set to true, missing "`$GIT_DIR/logs/<ref>`"
+	variable is set to `true`, missing "`$GIT_DIR/logs/<ref>`"
 	file is automatically created for branch heads (i.e. under
-	refs/heads/), remote refs (i.e. under refs/remotes/),
-	note refs (i.e. under refs/notes/), and the symbolic ref HEAD.
+	`refs/heads/`), remote refs (i.e. under `refs/remotes/`),
+	note refs (i.e. under `refs/notes/`), and the symbolic ref `HEAD`.
 +
 This information can be used to determine what commit
 was the tip of a branch "2 days ago".