Update readme.txt to include Custom Pack Uploader (coming soon)

git-svn-id: https://plugins.svn.wordpress.org/svg-vector-icon-plugin/trunk@835795 b8457f37-d9ea-0310-8a92-e5e31aec5664
update readme.txt error

git-svn-id: https://plugins.svn.wordpress.org/svg-vector-icon-plugin/trunk@835796 b8457f37-d9ea-0310-8a92-e5e31aec5664