FAQ needs updating to reflect fluxcd.io/ignore annotation

[racdev]

In the Flux v1 documentation, the FAQ documents the fluxcd.io/ignore annotation and how it can be used to ignore particular manifests (https://docs.fluxcd.io/en/1.21.0/faq/#can-i-temporarily-make-flux-ignore-a-manifest) during reconciliation.

In Flux v2, the annotation isn't supported. There is no mention of it in the Flux 2 documentation and this could cause issues for people migrating from Flux v1 who aren't aware it isn't supported, and who regularly use the annotation or have it currently set in their committed code.

The Flux 2 FAQ should be updated to state the annotation isn't supported as well as detailing the equivalent mechanism(s) available in Flux v2, to achieve the same affect.