Fixed #11519 -- Corrected minor typo in release notes index.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@11338 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/releases/index.txt

@@ -3,7 +3,7 @@
 Release notes
 =============
 
-Releases notes for the official Django releases. Each release note will tell you
+Release notes for the official Django releases. Each release note will tell you
 what's new in each version, and will also describe any backwards-incompatible
 changes made in that version.