Inline doc improvements for bp-activity-akismet.php

See #5022

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7395 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Inline doc improvements for bp-activity-cache.php

See #5022

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7396 cdf35c40-ae34-48e0-9cc9-0c9da1808c22