Add note about `core/ptr/mod.rs` changes that un-constified many things, apparently temporarily
Hopefully this is fixed quickly enough not to require a version bump. Why is it always the most useful things in Rust that always get broken for relatively unexpected / obscure reasons?
+**Note:** I am aware that changes were made on around June 4th that reverted the constness of various pointer methods. As these have been explicitly stated as temporary in the relevant PRs, no "fix version" of this crate will be issued unless the changes in question prove to be stretching the truth about how temporary they actually are.
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