Extend the organisation's Renovate preset

Without this the preset applies to nothing: a repository with no renovate.json
falls back on Renovate's own defaults, and the org's decisions — what may merge
itself, and what may not — reach it not at all.

Author: tannevaled

renovate.json

@@ -0,0 +1,4 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": ["github>go-webengine/.github"]
+}