[RN] Remove obsolete comment

We have already made the implicit decision not to pursue what the
comment describes. If we ever revisit it, it probably won't be handled
where the comment is anyway.

react/features/app/actions.js

 function _appNavigateToMandatoryLocation(
         dispatch: Dispatch<*>, getState: Function,
         newLocation: Object) {
-    // TODO Kostiantyn Tsaregradskyi: We should probably detect if user is
-    // currently in a conference and ask her if she wants to close the
-    // current conference and start a new one with the new room name or
-    // domain.
-
     const oldLocationURL = getState()['features/base/connection'].locationURL;
     const oldHost = oldLocationURL ? oldLocationURL.host : undefined;
     const newHost = newLocation.host;