One other 5.0a1 date to fix

Author: nedbat

doc/index.rst

@@ -77,7 +77,7 @@ not.
 
 .. ifconfig:: prerelease
 
-    The latest version is coverage.py 5.0a1, released May 28th 2018.  It is
+    The latest version is coverage.py 5.0a1, released June 5th 2018.  It is
     supported on:
 
     * Python versions 2.7, 3.4, 3.5, 3.6, and 3.7.