Improve svnsync help output.
Improve svnsync help output.

Patch by: David Glasser <glasser@mit.edu>

* subversion/svnsync/main.c
  (svnsync_command_table): Describe the requirements for svnsync
   in "svnsync help init".

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