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.