add bundle clean to upgrade docs

doc/update/8.4-to-8.5.md

@@ -64,6 +64,9 @@ sudo -u git -H bundle install --without postgres development test --deployment
 # PostgreSQL installations (note: the line below states '--without mysql')
 sudo -u git -H bundle install --without mysql development test --deployment
+# Clean up old gems
+sudo -u git -H bundle clean
+
 # Run database migrations
 sudo -u git -H bundle exec rake db:migrate RAILS_ENV=production

doc/update/patch_versions.md

@@ -62,6 +62,7 @@ sudo -u git -H bundle install --without development test mysql --deployment
 # MySQL
 sudo -u git -H bundle install --without development test postgres --deployment
+sudo -u git -H bundle clean
 sudo -u git -H bundle exec rake db:migrate RAILS_ENV=production
 sudo -u git -H bundle exec rake assets:clean assets:precompile cache:clear RAILS_ENV=production
 ```