Fix name of `Gerrit-Has-Labels` email footer

The name is actually `Gerrit-Has-Labels`, not `Gerrit-HasLabels`. The
email footers do not follow a consistent naming schema, some of them use
dashes and others use camelcase. This label, contrary to the current
documentation, uses dashes.

Release-Notes: skip
Google-Bug-Id: b/291061494
Change-Id: Iae5e49cfa00c95800838599375d231801c6cd0c8
(cherry picked from commit 9da5f5d99b1c8e8e60f572abaa11a99bb46a6fa7)
diff --git a/Documentation/user-notify.txt b/Documentation/user-notify.txt
index f420fe7..2da3802 100644
--- a/Documentation/user-notify.txt
+++ b/Documentation/user-notify.txt
@@ -245,11 +245,11 @@
 comments had been posted in that notification using "Yes" or "No", for
 example `Gerrit-HasComments: Yes`.
 
-[[Gerrit-HasLabels]]Gerrit-HasLabels::
+[[Gerrit-Has-Labels]]Gerrit-Has-Labels::
 
 In comment emails, the has-labels footer states whether label votes had
 been posted in that notification using "Yes" or "No", for
-example `Gerrit-HasLabels: No`.
+example `Gerrit-Has-Labels: No`.
 
 [[Gerrit-Comment-In-Reply-To]]Gerrit-Comment-In-Reply-To::