Tools/scripts: remove addport

The addport script is no longer useful since git has been introduced in
April 2021, just use plain "git add" instead. Do not forget to add the
port name to the category Makefile and mention the contributor in the
contributors article in the doc repository.

Differential Revision: https://reviews.freebsd.org/D35104

Author: rene0

Tools/scripts/README

@@ -5,7 +5,6 @@ NOTE: These scripts need work and are *NOT* safe to use unless you know
 
 MOVEDlint.awk - checks MOVED for common errors
 ardiff	- compare two archives easily
-addport	- replacement for easy-import
 bad-pkgdescrs.sh - locate identical pkg descriptions
 bump_revision.pl - Small script to bump the PORTREVISION variable of ports
                    which are depending on a port with a changed shared lib