Explain and streamline upgrade steps

doc/update/6.2-to-6.3.md

@@ -46,10 +46,11 @@ sudo -u git -H bundle install --without development test postgres --deployment
 sudo -u git -H bundle install --without development test mysql --deployment
 
 
+# Run database migrations
 sudo -u git -H bundle exec rake db:migrate RAILS_ENV=production
-sudo -u git -H bundle exec rake assets:clean RAILS_ENV=production
-sudo -u git -H bundle exec rake assets:precompile RAILS_ENV=production
-sudo -u git -H bundle exec rake cache:clear RAILS_ENV=production
+
+# Clean up assets and cache
+sudo -u git -H bundle exec rake assets:clean assets:precompile cache:clear RAILS_ENV=production
 ```
 
 ### 5. Update config files