Update testimonials

[dholbach]

After last KubeCon and our last GitOps One-Stop Event, we should be able to update some of the endorsements on the landing page, with e.g. recordings from AWS, Azure, D2IQ, Red Hat, VMware and the Platform One team - wdyt @staceypotter ?

[kingdonb]

Since these companies are all building products based on Flux, I think that sounds entirely reasonable

[dholbach]

https://www.cncf.io/blog/2021/09/30/how-to-get-robust-gitops-the-u-s-department-of-defense-uses-flux-and-helm/ would be another good one