updated docs

Signed-off-by: Prune <prune@lecentre.net>

Author: prune998

docs/docs/50-user-guide/60-reference-docs/30-promotion-steps/yaml-merge.md

@@ -11,6 +11,14 @@ file and is commonly followed by a [`helm-template` step](helm-template.md).
 YAML files are merged in order, so the first one is the base, and all
 subsequent files are "overlays", modifying the default values.
 
+:::note
+Merging is done with usual constrains:
+- new objects are merged
+- object with same name are modified
+- lists are replaced by latest version (no merge)
+- null values delete the object
+:::
+
 ## Configuration
 
 | Name | Type | Required | Description |

pkg/x/promotion/runner/builtin/zz_config_types.go

@@ -1,25 +1,25 @@
 {
-  "$schema": "https://json-schema.org/draft/2020-12/schema",
-  "title": "YAMLMergeConfig",
-  "type": "object",
-  "additionalProperties": false,
-  "properties": {
-    "inPaths": {
-      "type": "array",
-      "description": "InPaths is the list of paths of YAML files to merge",
-      "items": {
-        "type": "string"
-      }
-    },
-    "outPath": {
-      "type": "string",
-      "description": "OutPath is the path to the merged YAML file to create or update.",
-      "minLength": 1
-    },
-    "strict": {
-      "type": "boolean",
-      "description": "Strict will cause the directive to fail if the input path does not exist.",
-      "default": false
-    }
+ "$schema": "https://json-schema.org/draft/2020-12/schema",
+ "title": "YAMLMergeConfig",
+ "type": "object",
+ "additionalProperties": false,
+ "properties": {
+  "inPaths": {
+   "type": "array",
+   "description": "InPaths is the list of paths of YAML files to merge",
+   "items": {
+    "type": "string"
+   }
+  },
+  "outPath": {
+   "type": "string",
+   "description": "OutPath is the path to the merged YAML file to created or updated.",
+   "minLength": 1
+  },
+  "strict": {
+   "type": "boolean",
+   "description": "Strict will cause the directive to fail if the input path does not exist.",
+   "default": false
   }
-}
+ }
+}