chore: Configure Renovate (#40)

## Action Required: Fix Renovate Configuration

There is an error with this repository's Renovate configuration that
needs to be fixed. As a precaution, Renovate will stop PRs until it is
resolved.

Location: `renovate.json`
Error type: Invalid JSON (parsing failed)
Message: Syntax error: expecting String near ],
  },
  


Once you have resolved this problem (in this onboarding branch),
Renovate will return to providing you with a preview of your
repository's configuration.

renovate.json

@@ -0,0 +1,13 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": ["config:recommended", ":enablePreCommit"],
+  "flux": {
+    "fileMatch": ["^cluster/.+\\.ya?ml$"]
+  },
+  "helm-values": {
+    "fileMatch": ["^cluster/.+\\.ya?ml$"]
+  },
+  "kubernetes": {
+    "fileMatch": ["^cluster/.+\\.ya?ml$"]
+  }
+}