Add comment on version pinning for acts-as-taggable-on.
Add comment on version pinning for acts-as-taggable-on.

hauledev/bookyt,gaapt/bookyt,silvermind/bookyt,xuewenfei/bookyt,xuewenfei/bookyt,gaapt/bookyt,huerlisi/bookyt,silvermind/bookyt,huerlisi/bookyt,wtag/bookyt,xuewenfei/bookyt,gaapt/bookyt,hauledev/bookyt,wtag/bookyt,hauledev/bookyt,gaapt/bookyt,silvermind/bookyt,hauledev/bookyt,huerlisi/bookyt,wtag/bookyt,silvermind/bookyt