Correlations: Add better handling to correlation type and update documentation (#109922)

* Add better type handling when correlation is created from provisioning and fix documentation

* add external example

* change error when deprecated key is used

docs/sources/administration/correlations/create-a-new-correlation/index.md

@@ -52,8 +52,8 @@ datasources:
       - targetUID: uid
         label: "test"
         description: "..."
+        type: query
         config:
-          type: "query"
           target:
             expr: "..."
           field: "name"
@@ -64,6 +64,14 @@ datasources:
               mapValue: "other"
             - type: logfmt
               field: "test"
+      - targetUID: uid2
+        label: "test 2"
+        description: "..."
+        type: external
+        config:
+          target:
+            url: "http://${example}"
+          field: "name"
 ```
 
 Description of provisioning properties:
@@ -77,12 +85,12 @@ Description of provisioning properties:
 **description**
 : Optional description
 
+**type**
+: Correlation type. Valid values are "query" for linking to a data source query and "external" for linking to an external URL.
+
 **config**
 : Config object
 
-**config.type**
-: Correlation type. Valid values are "query" for linking to a data source query and "external" for linking to an external URL.
-
 **config.target**
 : [Target query model](#determine-target-query-model-structure)