This gives a baseline for future changes, e.g., expanding where
namespace ACLs are used, switching access control to
untrusted-by-default.

The "Security considerations" section  was adapted from

    https://github.com/fluxcd/flux2/pull/2086



Signed-off-by: Michael Bridgen <michael@weave.works>

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

The RFC template is heavily inspired by Rust RFCs and Kubernetes KEPs.

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>