Bug 1650785 - Improve discoverability of geckoview telemetry docs r=Dexter

Differential Revision: https://phabricator.services.mozilla.com/D82381

toolkit/components/telemetry/docs/collection/histograms.rst

@@ -238,6 +238,7 @@ Required. This field is a list of products this histogram can be recorded on. Cu
 
 - ``firefox`` - Collected in Firefox Desktop for submission via Firefox Telemetry.
 - ``fennec`` - Collected in Firefox for Android for submission via Firefox Mobile Telemetry.
+- ``geckoview_streaming`` - See :doc:`this guide <../start/report-gecko-telemetry-in-glean>` for how to stream data through geckoview to the Glean SDK.
 
 ``record_into_store``
 ---------------------

toolkit/components/telemetry/docs/collection/scalars.rst

@@ -168,6 +168,7 @@ Required Fields
 
   - ``firefox`` - Collected in Firefox Desktop for submission via Firefox Telemetry.
   - ``fennec`` - Collected in Firefox for Android for submission via Firefox Mobile Telemetry.
+  - ``geckoview_streaming`` - See :doc:`this guide <../start/report-gecko-telemetry-in-glean>` for how to stream data through geckoview to the Glean SDK.
 
 - ``record_in_processes``: A list of processes the scalar is allowed to record in. Currently supported values are:
 

toolkit/components/telemetry/docs/internals/geckoview-streaming.rst

@@ -1,12 +1,15 @@
 GeckoView Streaming API
 =======================
 
-As an alternative to :doc:`GeckoView <../internals/geckoview>` mode,
+As an alternative to the normal mode where Firefox Desktop records and sends data,
 Telemetry can instead route Histogram samples and Scalar values out of Gecko to a Telemetry Delegate.
 
 To do this, ``toolkit.telemetry.geckoview.streaming`` must be set to true,
 and Gecko must have been built with ``MOZ_WIDGET_ANDROID`` defined.
 
+See :doc:`this guide <../start/report-gecko-telemetry-in-glean>`
+for how to collect data in this mode.
+
 Details
 =======