Document the package prefix.
Document the package prefix.

Review by: xsteve
(the text, but not its exact placement)

* contrib/client-side/psvn/psvn.el:
    Added a comment about the prefixes this package uses in its symbols.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion