Bug 1097107 - Fix a few errors in the protocol.js docs. r=fitzgen

toolkit/devtools/server/docs/protocol.js.md

@@ -78,7 +78,8 @@ How do you get an initial reference to the front?  That's a bit tricky, but basi
 * Magically
 
 Manually - If you're using a DebuggerClient instance, you can discover the actorID manually and create a Front for it:
-  let hello = HelloFront(this.client, { actorID: <hello actorID> });
+
+    let hello = HelloFront(this.client, { actor: <hello actorID> });
 
 Magically - Once you have an initial reference to a protocol.js object, it can return other protocol.js objects and fronts will automatically be created.