Add ignore_errors for memcached readme.txt
Add ignore_errors for memcached readme.txt

This was supposed to be in I6b36db7b7ce8b3e4da566eb7828d0c3b8646a14f
but i missed it on the edit because memcached doesn't have its own
directory, so it didn't match the regex i created to edit the
patch. Apologies for the patch churn on this. This fix has been
directly incorporated into I6b36db7b7ce8b3e4da566eb7828d0c3b8646a14f
backport, so we at least won't need to backport this oneliner.

Change-Id: I31d8adf72ea6c3544e534dca57c5c415e2908674
Partial-Bug: #1730957

dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,openstack/tripleo-heat-templates,dprince/tripleo-heat-templates