Update documentation link on project page

There is also this related doc page, Mix public and private files with Organic Groups and File (Field) Paths → . Should that be migrated or can it be deleted. Probably best to respond at #3442232: Decide what to with TO BE MIGRATED →

@quietone,

Thank you for taking care about docs migration.

• I've updated the project page with the correct link to Drupal 7 documentation
• Added a comment at #3442232-23: Decide what to do with TO BE MIGRATED → regarding "Mix public and private files with Organic Groups and File (Field) Paths"
• Created 📌 Create Drupal >=10 documentation Active as follow-up for Drupal >=10 documentation

Please mark this as Fixed if you consider everything is OK.