Update Project page to direct users to a download they can use for Drupal installtion

As two users in IRC had problems installing a localized Drupal version I went through the prcess to figure out what the problem ist:

During installation the user is promted to "Choose language".
Now that we have localize.drupal.org the help text is a bit confusing:

Choose language

With the addition of an appropriate translation package, this installer is capable of proceeding in another language of your choice. To install and use Drupal in a language other than English:

• Determine if a translation of this Drupal version is available in your language of choice. A translation is provided via a translation package; each translation package enables the display of a specific version of Drupal in a specific language. Not all languages are available for every version of Drupal.
• If an alternative translation package of your choice is available, download and extract its contents to your Drupal root directory.
• Return to choose language using the second link below and select your desired language from the displayed list. Reloading the page allows the list to automatically adjust to the presence of new translation packages.

Alternatively, to install and use Drupal in English, or to defer the selection of an alternative language until after installation, select the first link below.

How should the installation continue?

• Continue installation in English
• Return to choose a language

If the user klicks on the link a translation of this Drupal version to seach for the German version he will fist find drupal.org/project/de where he/she is forwarded to http://localize.drupal.org/translate/languages/de
At this page the german Version is supplied as one de.po file. This unfortunately does not work for the installation process. Instead what the user would need ist http://localize.drupal.org/translate/languages/de/export

Now there probably is already an issue that the whole process is too complicated etc. but we can have an easy win if we point the user to http://localize.drupal.org/translate/languages/de/export as well and describe the difference. (Here on the project page as well as on http://localize.drupal.org/translate/languages/de)

Proposal for the project page:

Translation of the Drupal interface to German.

To download the most recent translation, please see http://localize.drupal.org/download.

If you were sent here during Drupal installation process you probably want the translation as an Installation package. (You need to be logged in to access this page) What is the difference between the single de.po file and the translation package?

The German translation is maintained at the translation server at http://localize.drupal.org/translate/languages/de.

"What is the difference between the single de.po file and the translation package?" should probably be a documentation page.