Correct capitalization of links
Correct typos
Remove spurious arguments to xargs

Also only run svn add if we have arguments.  This commit addresses
these warnings:

svn: warning: '{}' not found
svn: warning: ';' not found

svn: Try 'svn help' for more info
svn: Not enough arguments provided
Update to indicate new location of API Keys
Update Google Groups to Apache mailing lists
Adding 1.6.2 release notes