Launch per-forum activity chart feature

This CL also adds to docs/features.md info about the feature.

Fixed: twpowertools:92
Change-Id: Iad99acd7e720677d65ca45f35b9a34d9084eeb1a
diff --git a/src/common/optionsPrototype.json5 b/src/common/optionsPrototype.json5
index 4ff1752..5866b0e 100644
--- a/src/common/optionsPrototype.json5
+++ b/src/common/optionsPrototype.json5
@@ -119,6 +119,11 @@
     killSwitchType: 'option',
   },
   // #!endif
+  'perforumstats': {
+    defaultValue: false,
+    context: 'options',
+    killSwitchType: 'option',
+  },
 
   // Experiments:
   'workflows': {
@@ -131,11 +136,6 @@
     context: 'experiments',
     killSwitchType: 'experiment',
   },
-  'perforumstats': {
-    defaultValue: false,
-    context: 'experiments',
-    killSwitchType: 'experiment',
-  },
 
   // Internal options:
   'ccdarktheme_switch_enabled': {