textproc/docproj: Add vale OPTION

After the introduction of vale through
https://cgit.freebsd.org/doc/commit/?id=2f326706331e23173f726dc3555cb74c9d23696d
it is necessary to introduce the tools for the developers. The
developers needs to install it. Hence add it in the meta-port so that we
can update the documentation to help the users use it.

PR: 267699
Approved by: dbaio