Update module summary for Project Browser and Drupal.org

If you update the "summary" of the Body field on your project's node page, you can control what's shown in Project Browser on the card, and on Drupal.org.

We discussed the project at #3360109: Migrate Tools - create a short description

We suggest the following summary for your project:

This module provides tools for running and managing Drupal migrations. A web UI provides a front-end equivalent to many of the Drush commands.