Add release script

This is useful to speed up the release process and avoid making
mistakes.

release.sh

@@ -0,0 +1,32 @@
+#!/bin/sh -eu
+
+prev=$(git describe --tags --abbrev=0)
+next=$(meson rewrite kwargs info project / | jq -r '.kwargs["project#/"].version')
+
+case "$next" in
+*-dev)
+	echo "This is a development version"
+	exit 1
+	;;
+esac
+
+if [ "$prev" = "$next" ]; then
+	echo "Version not bumped in meson.build"
+	exit 1
+fi
+
+if ! git diff-index --quiet HEAD -- meson.build; then
+	echo "meson.build not committed"
+	exit 1
+fi
+
+shortlog="$(git shortlog --no-merges "$prev..")"
+(echo "wlroots $next"; echo ""; echo "$shortlog") | git tag "$next" -ase -F -
+
+prefix=wlroots-$next
+archive=$prefix.tar.gz
+git archive --prefix="$prefix/" -o "$archive" "$next"
+gpg --output "$archive".sig --detach-sig "$archive"
+
+git push --follow-tags
+glab release create "$next" "$archive" "$archive.sig" --notes ""