Bug 1349256 - Merged server and general docs under just one directory; r=sole

MozReview-Commit-ID: HzNGfWhYukh

--HG--
rename : devtools/server/docs/actor-e10s-handling.md => devtools/docs/backend/actor-e10s-handling.md
rename : devtools/server/docs/actor-hierarchy.md => devtools/docs/backend/actor-hierarchy.md
rename : devtools/server/docs/actor-registration.md => devtools/docs/backend/actor-registration.md
rename : devtools/server/docs/protocol.js.md => devtools/docs/backend/protocol.js.md
extra : rebase_source : 79e5b6d50a24912315dac470de2cd32a3608488e

devtools/docs/SUMMARY.md

@@ -18,6 +18,11 @@
     * [Guidelines](frontend/redux-guidelines.md)
     * [Tips](frontend/redux-tips.md)
 * [Backend](backend/backend.md)
-  * [Protocol](backend/protocol.md)
+  * [Remote Debugging Protocol](backend/protocol.md)
   * [Debugger API](backend/debugger-api.md)
   * [Backward Compatibility](backend/backward-compatibility.md)
+  * Actors
+    * [Actors Organization](backend/actor-hierarchy.md)
+    * [Handling Multi-Processes in Actors](backend/actor-e10s-handling.md)
+    * [Writing Actors With protocol.js](backend/protocol.js.md)
+    * [Registering A New Actor](backend/actor-registration.md)