Correct errors preventing proper display of Riak CS GC document

Correct some issues with malformed version guards preventing the
display of most of the information in the Riak CS garbage collection
document for the 1.5.0 version.
fix tr version strip regexp
left a scalpal in the patient
Merge pull request #1277 from basho/bugfix/missing-cs-gc-data

Correct errors preventing proper display of Riak CS GC document