add envoy gateway documentation

[sabban]

add envoy gateway documentation

[aws-amplify-eu-west-1]

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[buixor]

• in the crowdsec install part (plz modify for nginx ingress too), be sure to suggest the good defaults especially for key mgmtm, auto-delete etc.
• add a test section with either .env (or better : the dedicated test scenario)
• armonize next steps with ie. nginx ingress
• also add it to the remediation component section

[sabban]

• in the crowdsec install part (plz modify for nginx ingress too), be sure to suggest the good defaults especially for key mgmtm, auto-delete etc.

I'll do this in another PR. auto-delete and flush are database configuration items, so this goes in the general Kubernetes configuration setup.