Merge branch 'ayduns-master-patch-27201' into 'master'

Links to migration guide

See merge request !76

docs/backdrop/index.md

@@ -5,6 +5,10 @@
     1. [Install Backdrop](https://backdropcms.org/installation), and...
     1. [Review the CiviCRM requirements](../general/requirements.md)
 
+???+ tldr "Migrating from Drupal 7"?
+
+    If you are migrating to Backdrop from Drupal 7, see [Switch from Drupal to Backdrop](https://docs.civicrm.org/sysadmin/en/latest/misc/switching-cms/drupal-to-backdrop/) in the [System Administrator Guide](https://docs.civicrm.org/sysadmin/en/latest).
+
 ??? tldr "Alternative: Civibuild for developers"
 
     If you plan to develop patches for CiviCRM on Backdrop, then please read the [Developer Guide](https://docs.civicrm.org/dev/en/latest) for information about [Buildkit](https://docs.civicrm.org/dev/en/latest/tools/buildkit/) and [civibuild](https://docs.civicrm.org/dev/en/latest/tools/civibuild/).