Serathius is focused on etcd these days, we shouldn't rely on him anymore for
approvals. Mengjiao has been very active with logging and would be a good
addition to the pool of reviewers.

I myself (pohly) have been the de-facto maintainer. Being able to approve
changes from others will be useful and I'll be careful to get a
second approver for my own changes.

OWNERS: remove serathius, add mengjiao-liu, promote pohly

With klogr being deprecated there might be some confusion whether
textlogger or klog.Background should be used instead.

docs: clarify relationship between different features

Add SafePtr wrapper

This moves slog support into the main package. Go >1.18 is needed for generic
type parameters.

This is syntactic sugar, but it's still useful because it hides logr from
developers who only care about klog and slog.

logr v1.4.0 moved the slog support functions in the main package and deprecated
slogr.

logr v1.4.1 + SetSlogLogger

One use case is to use Ginkgo for stack unwinding. Then `ginkgo.GingkgoHelper`
also works for log output, not just for E2E failures.