--- a/toolkit/components/telemetry/docs/data/main-ping.rst
+++ b/toolkit/components/telemetry/docs/data/main-ping.rst
@@ -112,16 +112,17 @@ Structure:
 .. code-block:: js
 
     "processes" : {
       // ... other processes ...
       "parent": {
         scalars: {...},
         keyedScalars: {...},
         events: {...},
+        // parent process histograms and keyedHistograms are in main payload
       },
       "content": {
         scalars: {...},
         keyedScalars: {...},
         histograms: {...},
         keyedHistograms: {...},
         events: {...},
       },