Add predefined managers; enable branch & commit prefixes

Author: lukasgabriel

renovate.json5

@@ -1,9 +1,14 @@
 {
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
   "extends": [
-    "config:recommended"
+    "config:recommended",
+    "customManagers:dockerfileVersions",
+    "customManagers:helmChartYamlAppVersions"
   ],
 
+  "branchPrefix": "deps/",
+  "semanticCommits": "enabled",
+
   "customManagers": [
     {
       "description": "Ubuntu package versions in Helm values",  // adapted from https://docs.renovatebot.com/modules/datasource/deb/#usage-example