Add php docs build script

Signed-off-by: Julius Härtl <jus@bitgrid.net>

build/phpDocumentor.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+# Use a cached version of phpDocumentor for now since there is no release yet
+# and the github actions artifacts might disappear
+# This phar is downloaded from https://github.com/phpDocumentor/phpDocumentor/actions/runs/221599704
+
+wget https://bitgrid.net/~jus/phpDocumentor.phar
+
+mkdir -p api/
+
+php7.4 phpDocumentor.phar -t "./api" -d "./lib/public" --title="Nextcloud PHP API (`git rev-parse --abbrev-ref HEAD`)"