Add build script for cover letters

scripts/letter.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+hash="$(git rev-parse HEAD)"
+body="<text>$(pandoc --from=markdown $1)</text>"
+company="$2" || ""
+date="$(date +'%d %B %Y')"
+signature="$(base64 ./assets/signature.svg)"
+
+mkdir -p ../dist
+
+echo $body | xsltproc --stringparam company "$company" --stringparam date "$date" --stringparam signature "$signature" ./templates/letter.xsl - > ./dist/letter.html
+weasyprint --quiet ./dist/letter.html ./dist/letter.pdf