Update INSTALL.txt for make file

Yes, please update INSTALL.txt to avoid user confusion. Also, the drupal-org.make file passes verification, but git cloning for most (actually, it looks like 'all') of the non-stable modules is failing. Here's what I'm seeing:

Unable to clone ns_core from                                         [error]
git://git.drupal.org/project/ns_core.git.
Unable to clone defaultconfig from                                   [error]
git://git.drupal.org/project/defaultconfig.git.
Unable to clone ctools from git://git.drupal.org/project/ctools.git. [error]
Unable to clone uuid from git://git.drupal.org/project/uuid.git.     [error]
Unable to clone views_rss from                                       [error]
git://git.drupal.org/project/views_rss.git.
Unable to clone draggableviews from                                  [error]
git://git.drupal.org/project/draggableviews.git.
Unable to clone wysiwyg from                                         [error]
git://git.drupal.org/project/wysiwyg.git.
Unable to clone media_youtube from                                   [error]
git://git.drupal.org/project/media_youtube.git.
Unable to clone pathfilter from                                      [error]
git://git.drupal.org/project/pathfilter.git.
Unable to clone admin_menu from                                      [error]
git://git.drupal.org/project/admin_menu.git.
Unable to clone entityreference from                                 [error]
git://git.drupal.org/project/entityreference.git.
Unable to clone crossclone from                                      [error]
git://git.drupal.org/project/crossclone.git.
Unable to clone panels_ref_formatter from                            [error]
git://git.drupal.org/project/panels_ref_formatter.git.

Here's a patch for the drupal-org.make file as well.

@paskainos We actually had to do that change in order to get Drupal.org to build the site for us. drush make should be fine using this, since it uses git.drupal.org as a default git server. Which version of drush and drush make are you using?

I updated the txt file. I also opened another issue, #1440668: Possible issue with the new make file structure for the drush make issue, so we can resolve that separately without delaying this patch.

Was using Drush 4.5 / Drush Make 2.3... Just drush selfupdate'ed to 7.x-5.0-rc2 (including Drush Make #1310130: Put drush make in drush core) so now I'm using Drush 5.0-rc2 / Drush Make API version 2. S'pose I'll give that a try...

Update: I was subsequently experiencing this issue: #1437150: PHP Warnings: "Unable to parse URL environment.inc:295". So I switched to Drush 5.0-dev based on the patch commit for that issue.

NOTE: I'll make all further posts on this in the other issue: #1440668: Change the standard git url for drupal.org from git:// to http://.