Document ingress containers must not be in hostNetwork mode

Nobody has claimed this yet.

### What problem are you trying to solve?

Setting up an Nginx ingress per this page - https://linkerd.io/2.11/tasks/using-ingress/ - won't work if the ingress controller (at least Nginx, but others no doubt) is in host mode. It's a known problem, but only after you figure out why linkerd isn't being injected (https://github.com/linkerd/linkerd2/issues/7949).

This is the default install mode for Rancher's rke2 / rke2-ingress-nginx, to run with `hostNetwork: true`

### How should the problem be solved?

At least, add a note on the https://linkerd.io/2.11/tasks/using-ingress/ page about the ingress cannot be running in host mode.

It'd be neat if the check tool detected annotations applied to pods, but the extra containers aren't deployed too. (This check tool is super neat too btw, as is the whole project.)

Another option is https://github.com/linkerd/linkerd2/issues/3330

### Any alternatives you've considered?

Alternative I applied was to remove hostNetwork mode from my ingress.

### How would users interact with this feature?

Reading

### Would you like to work on this feature?

maybe

Start with the linked 2.11 tasks/using-ingress/ page and review how it explains ingress controller setup. Document that ingress controllers using hostNetwork, including the described Nginx setup, are incompatible with injection; the work is done when readers can find this limitation and the alternative configuration guidance.

Written by the indexing model from the issue text.