docs: link issue for update in CPU/battery analyses (#537)

Signed-off-by: Michael Rebello <[email protected]>
Signed-off-by: JP Simard <[email protected]>

mobile/docs/root/development/performance/cpu_battery_impact.rst

@@ -3,6 +3,11 @@
 Analysis of CPU/battery impact
 ==============================
 
+.. warning::
+
+  These analyses have not been updated since Envoy Mobile added interfaces for performing
+  network requests directly using the library. They will be re-run as part of :issue:`#536 <536>`.
+
 Modified versions of the "hello world" example apps were used to run these experiments:
 
 - :tree:`Android control app <8636711/examples/kotlin/control>`
@@ -44,8 +49,6 @@ Android
 
 Valid through SHA :tree:`8636711 <8636711>`.
 
-TODO(buildbreaker): Update battery percentages
-
 Envoy:
 
 - Avg CPU: 33.16075949%