ietf-nntp References to PAT still present

[Russell Vincent]

Another possible change with the HDR command needed:

Section 13 (BNF Syntax) still has reference to the PAT command and
the "hdr-command" line should be changed to replace PAT with HDR.

Also, section 9.5.3 states:

   This extension provides one new command, HDR. The label for
   this extension is PAT.

Should the label for the extension should be HDR and not PAT?
If so, the following should also be updated:

  8.1.1.1 (LIST EXTENSIONS Examples) should change from PAT to HDR.

I gather the history of this was that the PAT command has been
replaced with the HDR command to avoid complications being introduced
with wildmats used for pattern matching in PAT. PAT has been
relegated to an extension documented separately if deemed necessary.
HDR does not use wildmats and is probably useful to keep.

 -Russell