RV+Toolkit—what does that mean?

With RV 7.0, the standard Shotgun integration—known as SG Review—is supplied by Shotgun Toolkit code that is distributed with RV.  Installing Shotgun Toolkit is not required to run RV 7.0 or the Toolkit components distributed with it. All code is written in Python and installed with RV.

In future releases, this will allow Toolkit apps to be versioned independently from RV and for the RV Toolkit engine to host user-developed apps.
Finally, since the SGTK RV Package is loaded by default, the SG Review menu will appear as soon as you authenticate RV with Shotgun. If you do not wish to use any SG Review features, you can uninstall the package or set the env var RV_SHOTGUN_NO_SG_REVIEW_MENU.