message: Add instructions on how to reset docker volumes
diff: @@ -137,6 +137,12 @@ To rebuild the site, run `docker-compose build`.
  Note that docker-compose caches the build even if you change the source code,
  so this will be necessary anytime you make changes.
  +If you want to completely clean up the database, don't forget to remove the volumes too:
  +
  +```
  +$ docker-compose down --volumes
  +```
  +
  #### FAQ
  ##### I keep getting the error `standard_init_linux.go:211: exec user process caused "no such file or directory"` when I use docker-compose.
  