INSTALL.txt should refer to 5.x not 4.7

I think Line 9 of the INSTALL.txt file, for phpbb.module 5.x-1.1, should read:

Drupal 5.x

It currently reads:

Drupal 4.7.x (You can use it with 4.6, but you have to make some changes to forms).

...
Thanks for this module!