extdir.md

-To run manually:
+`extdir` handles both the [extension directory](https://civicrm.org/extensions) and also has a Drush command to scan/update known extensions for new releases.
+
+This runs from Jenkins:  
+https://test.civicrm.org/view/Sites/job/Extdir%20Scan%20(civicrm.org)/
+
+To run manually (from `www-prod-2`):
 
 ```
 sudo -i -u aegir
 drush @civicrm.org extdir-scan
 ```
 
-This is usually ran from Jenkins:  
-https://test.civicrm.org/view/Sites/job/Extdir%20Scan%20(civicrm.org)/
-
 Some documentation in the dev book:  
 https://docs.civicrm.org/dev/en/latest/extensions/publish/#publishing-a-civicrm-extension
+
+The code does not seem to have its own git repository. It is part of the `civicrm-org-platform` repo:  
+https://github.com/civicrm/civicrm-org-platform/tree/master/sites/all/modules/custom/extdir
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