Inconsistent terminology for -j/--jobs option in documentation

Hi,

While reading the pg_dump and pg_restore documentation, I noticed
that the terminology for the -j/--jobs option is inconsistent.

## pg_dump [1]
-j njobs
--jobs=njobs

## pg_restore [2]
-j number-of-jobs
--jobs=number-of-jobs

For the sake of consistency, I think it would be better to revise the
terminology as follows:

s/number-of-jobs/njobs/

To double-check, I also looked at the documentation for vacuumdb,
reindexdb, and pg_upgrade, and all of them use "njobs".

Please find the attached patch.

[1] https://www.postgresql.org/docs/current/app-pgdump.html
[2] https://www.postgresql.org/docs/current/app-pgrestore.html

Regards,
Tatsuro Yamada