Mention the push %l-parameter in the documentation

Change-Id: Icc564ca82c2e05d176f75ddfd3b11924dcabaabe

Documentation/user-upload.txt

diff --git a/Documentation/user-upload.txt b/Documentation/user-upload.txt
index b892c4a..933b008 100644
--- a/Documentation/user-upload.txt
+++ b/Documentation/user-upload.txt
@@ -155,6 +155,19 @@
   git push ssh://john.doe@git.example.com:29418/kernel/common HEAD:refs/for/experimental%topic=driver/i42
 ====
 
+Review labels can be applied to the change by using the -l option
+in the reference:
+
+====
+  git push ssh://john.doe@git.example.com:29418/kernel/common HEAD:refs/for/experimental%l=Verified+1
+====
+
+The `l='label[score]'` option may be specified more than once to
+apply multiple review labels.
+
+The value is optional.  If not specified, it defaults to +1 (if
+the label range allows it).
+
 If you are frequently uploading changes to the same Gerrit server,
 consider adding an SSH host block in `~/.ssh/config` to remember
 your username, hostname and port number.  This permits the use of