Add further notes to the upgrade process

docs/releases/1.1.rst

@@ -55,6 +55,8 @@ What's new in Mayan EDMS v1.1
 
 Upgrading from a previous version
 =================================
+IMPORTANT! Before running the upgrade make sure none of your documents have duplicated metadata types, meaning that the same metadata type appears twice for a given document.
+
 If you installed Mayan EDMS by cloning the Git repository issue the commands::
 
     $ git reset --hard HEAD
@@ -76,6 +78,35 @@ Migrate existing database schema with::
     $ mayan-edms.py migrate tags 0001 --fake
     $ mayan-edms.py migrate
 
+During the migration the message::
+
+The following content types are stale and need to be deleted:
+
+    ocr | documentqueue
+    ocr | queuedocument
+
+Any objects related to these content types by a foreign key will also
+be deleted. Are you sure you want to delete these content types?
+If you're unsure, answer 'no'.
+
+    Type 'yes' to continue, or 'no' to cancel:
+
+
+and
+
+The following content types are stale and need to be deleted:
+
+    tags | tagproperties
+
+Any objects related to these content types by a foreign key will also
+be deleted. Are you sure you want to delete these content types?
+If you're unsure, answer 'no'.
+
+    Type 'yes' to continue, or 'no' to cancel: 
+
+
+You can safely answer "yes" to both.
+
 Add new static media::
 
     $ mayan-edms.py collectstatic --noinput