psql: Fix category of \parse in output of --help=commands and \?

psql: Fix category of \parse in output of --help=commands and \?

\parse was listed under the category "Connection", which was incorrect.
Let's move it to "General" like the other meta-commands of the same type
(\bind, \bind_named and \close).

Oversight in commit d55322b0da60.

Discussion: https://postgr.es/m/Zz_x-NEKNeeRlAVc@paquier.xyz