docs: fix 7.7.1 release date

(cherry picked from commit e6f5ca0fa3)

docs/news.html

@@ -11,7 +11,7 @@
 <H1>News</H1>
 
 
-<h2>March 26, 2010</h2>
+<h2>March 28, 2010</h2>
 <p>
 <a href="relnotes-7.7.1.html">Mesa 7.7.1</a> is released.  This is a bug-fix
 release fixing issues found in the 7.7 release.