Adds customizable invite request copy

bookwyrm/models/site.py

@@ -24,7 +24,10 @@ class SiteSettings(models.Model):
 
     # about page
     registration_closed_text = models.TextField(
-        default="Contact an administrator to get an invite"
+        default='We aren\'t taking new users at this time. You can find an open instance at <a href="https://joinbookwyrm.com/instances">joinbookwyrm.com/instances</a>.'
+    )
+    invite_request_text = models.TextField(
+        default="If your request is approved, you will receive an email with a registration link."
     )
     code_of_conduct = models.TextField(default="Add a code of conduct here.")
     privacy_policy = models.TextField(default="Add a privacy policy here.")