add pkgup helper extension

extensions/pkgup.ksh

@@ -0,0 +1,14 @@
+#!/bin/ksh
+
+pkgup() {
+	local _up_url
+	_up_url="https://pintobyte.com/pkgup/"
+	[ ! -z $1 ] && _up_url=$1
+
+	if which obsdpkgup >/dev/null 2>&1; then
+		PKGUP_URL="$_up_url" obsdpkgup
+	else
+		echo "Please install obsdpkgup:"
+		echo "  GO111MODULE=on go get -u github.com/neutralinsomniac/obsdpkgup"
+	fi
+}

extensions/pkgup.org

@@ -0,0 +1,9 @@
+* pkgup
+
+~pkgup~ uses [[https://github.com/neutralinsomniac/obsdpkgup][obsdpkgup]] to provide [[https://man.openbsd.org/pkg_add][pkg_add]] a shortened list of packages that need
+updating. For more information on how this works, see `obsdpkgup`'s
+[[https://github.com/neutralinsomniac/obsdpkgup#rationale][documentation]].
+
+| Function | Description                                                             |
+|----------+-------------------------------------------------------------------------|
+| ~pkgup~  | Convenience function intended to have its result piped to ~pkg_add(1)~. |