Remove OpenFaaS CE user

It is our understanding from staff at NW that they are using
OpenFaaS CE in a production capacity for commercial
purposes.

This is in infringement to the OpenFaaS CE EULA.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

Author: alexellis

_data/customers.yml

@@ -35,8 +35,6 @@
   logo: cognite.png
 - name: LivePerson
   logo: liveperson.png
-- name: Northwestern Mutual
-  logo: nw.png
 - name: Virality
   logo: virality.png
 - name: T-Mobile USA