docs: add instruction for using OFO and GitOps

[thisthat]

This PR

adds some notes on a shortcoming of the compatibility of OFO with Applications deployed via GitOps.

Argo example

While deploying an App that makes use of FF via Argo, flagD was continuously failing with the following error log:

error   kubernetes/kubernetes_sync.go:115   error with the initial fetch: featureflagconfigurations.core.openfeature.dev "featureflagconfiguration-sample" is forbidden: User "system:serviceaccount:myawesomeapp:default" cannot get resource "featureflagconfigurations" in API group "core.openfeature.dev" in the namespace

After some debugging, we discovered that Argo was changing back the RoleBinding deployed with the Application.
We fixed the issue by adding the following info to the Argo App so it doesn't try to reconcile the Role Bindings changed by OFO:

ignoreDifferences:
  - group: "rbac.authorization.k8s.io"
    kind: "ClusterRoleBinding"
    jsonPointers:
    - /subjects  
...
syncOptions:
  - RespectIgnoreDifferences=true

[toddbaert]

I think this only impacts the kubernetes sync, but after looking through the doc, I don't think we do a great job describing the files/kubernetes/flagd-proxy syncs. I think the best place to put this would be in a section talking about the kubernetes sync.

How would you feel about adding this to @Kavindu-Dodan 's improved doc here: https://github.com/open-feature/open-feature-operator/pull/496/files#diff-c282aa25f1dabaaba19197006c4aa6bab00e8d2b2100375c42b41b7cf4bc55cbR14 ?

[thisthat]

@toddbaert sure thing! I'll wait until that PR is merged and then build on top of that 👍

[toddbaert]

Great. Nice find BTW!

[thisthat]

@toddbaert @Kavindu-Dodan @beeme1mr the PR is ready for review.

[toddbaert]

Left optional suggestions.

I think this is pretty much perfect, great addition.

[toddbaert]

@beeme1mr any concerns with merging this now?

[thisthat]

@beeme1mr ping