Proposal: adding a better description in psql command about large objects

Hello,

Attached is a small patch to add a description to the meta commands
regarding
large objects.

the actual description when using psql --help=commands is :

Large Objects
   \lo_export LOBOID FILE
   \lo_import FILE [COMMENT]
   \lo_list
   \lo_unlink LOBOID      large object operations

the proposed description is :

Large Objects
   \lo_export LOBOID FILE  export large object to a file
   \lo_import FILE [COMMENT]    import large object from a file
   \lo_list               list large objects
   \lo_unlink LOBOID      delete a large object

I tried to make an alignment on the description of other meta-commands.

Thanks.
Regards.
--
Thibaud W.