fix spacing in complex yaml example

Author: mr-c

_extras/yaml.md

@@ -148,19 +148,19 @@ and a more complex example combining maps and arrays:
 exclusive_parameters:
   type:
     - type: record
-      name: itemC
-      fields:
-        itemC:
-          type: string
-          inputBinding:
-            prefix: -C
+       name: itemC
+       fields:
+         itemC:
+           type: string
+           inputBinding:
+              prefix: -C
     - type: record
-      name: itemD
-      fields:
-        itemD:
-          type: string
-          inputBinding:
-            prefix: -D
+       name: itemD
+       fields:
+         itemD:
+            type: string
+            inputBinding:
+              prefix: -D
 ```
 
 ### JSON Style