[1.11.x] Removed unexpected initial attribute in data migration examples.

Inadvertently added in db97a88495.
Backport of 899c42cc8e from master

AUTHORS

@@ -718,6 +718,7 @@ answer newbie questions, and generally made Django that much better:
     Stanislaus Madueke
     starrynight <cmorgh@gmail.com>
     Stefane Fermgier <sf@fermigier.com>
+    Stefano Rivera <stefano@rivera.za.net>
     Stéphane Raimbault <stephane.raimbault@gmail.com>
     Stephan Jaekel <steph@rdev.info>
     Stephen Burrows <stephen.r.burrows@gmail.com>

docs/topics/migrations.txt

@@ -466,7 +466,6 @@ Then, open up the file; it should look something like this::
     from django.db import migrations
 
     class Migration(migrations.Migration):
-        initial = True
 
         dependencies = [
             ('yourappname', '0001_initial'),
@@ -504,7 +503,6 @@ need to do is use the historical model and iterate over the rows::
             person.save()
 
     class Migration(migrations.Migration):
-        initial = True
 
         dependencies = [
             ('yourappname', '0001_initial'),