Merge pull request 'Configure Renovate' (#1) from renovate/configure into main

Reviewed-on: https://git.nick-slowinski.de/nick-slowinski.de/docs/pulls/1

renovate.json

@@ -0,0 +1,3 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json"
+}