Doc: Formatting

Fixed formatting of json.

Combination of tabs and spaces made the json looks bad on
my device

Author: ErikDeSmedt

doc/developers-guide/plugin-development/hooks.md

@@ -608,23 +608,30 @@ The payload for a call follows this format:
 
 ```json
 {
-    "onion_message": {
-        "pathsecret": "0000000000000000000000000000000000000000000000000000000000000000",
-        "reply_first_node": "02df5ffe895c778e10f7742a6c5b8a0cefbe9465df58b92fadeb883752c8107c8f",
-        "reply_blinding": "02df5ffe895c778e10f7742a6c5b8a0cefbe9465df58b92fadeb883752c8107c8f",
-		"reply_path": [ {"id": "02df5ffe895c778e10f7742a6c5b8a0cefbe9465df58b92fadeb883752c8107c8f",
-                         "encrypted_recipient_data": "0a020d0d",
-                         "blinding": "02df5ffe895c778e10f7742a6c5b8a0cefbe9465df58b92fadeb883752c8107c8f"} ],
-        "invoice_request": "0a020d0d",
-		"invoice": "0a020d0d",
-		"invoice_error": "0a020d0d",
-		"unknown_fields": [ {"number": 12345, "value": "0a020d0d"} ]
-	}
+  "onion_message": {
+    "pathsecret": "0000000000000000000000000000000000000000000000000000000000000000",
+    "reply_first_node": "02df5ffe895c778e10f7742a6c5b8a0cefbe9465df58b92fadeb883752c8107c8f",
+    "reply_blinding": "02df5ffe895c778e10f7742a6c5b8a0cefbe9465df58b92fadeb883752c8107c8f",
+    "reply_path": [
+      {
+        "id": "02df5ffe895c778e10f7742a6c5b8a0cefbe9465df58b92fadeb883752c8107c8f",
+        "encrypted_recipient_data": "0a020d0d",
+        "blinding": "02df5ffe895c778e10f7742a6c5b8a0cefbe9465df58b92fadeb883752c8107c8f"
+      }
+    ],
+    "invoice_request": "0a020d0d",
+    "invoice": "0a020d0d",
+    "invoice_error": "0a020d0d",
+    "unknown_fields": [
+      {
+        "number": 12345,
+        "value": "0a020d0d"
+      }
+    ]
+  }
 }
 ```
 
-
-
 All fields shown here are optional.
 
 We suggest just returning `{'result': 'continue'}`; any other result will cause the message not to be handed to any other hooks.