gbproxy: The "[stats]" option was not documented, document it

Documentation error (missing docs):
<command id='show gbproxy [stats]'>
        <param name='[stats]' doc='(null)' />
1 file changed
tree: 4748b7f8d496df67cec79afcbc20b076d8872389
  1. debian/
  2. hlrsync/
  3. linux-kernel/
  4. openbsc/
  5. wireshark/
  6. README