Welcome screen: update rockstars for 2.1

git-svn-id: https://buddypress.svn.wordpress.org/trunk@9003 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Welcome screen: remove image TODO notes

See #5805

git-svn-id: https://buddypress.svn.wordpress.org/trunk@9004 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Welcome screen: fix broken link for "get started".

Fixes #5840, props mercime

git-svn-id: https://buddypress.svn.wordpress.org/trunk@9005 cdf35c40-ae34-48e0-9cc9-0c9da1808c22