Rollup merge of #125739 - RalfJung:drop-in-place-docs, r=workingjubilee

drop_in_place: weaken the claim of equivalence with drop(ptr.read())

The two are *not* semantically equivalent in all cases, so let's not be so definite about this.

Fixes https://github.com/rust-lang/rust/issues/112015

src/tools/miri/tests/pass/drop_in_place.rs

@@ -0,0 +1,12 @@
+// Miri currently doesn't require types without drop glue to be
+// valid when dropped. This test confirms that behavior.
+// This is not a stable guarantee!
+
+use std::ptr;
+
+fn main() {
+    let mut not_a_bool = 13u8;
+    unsafe {
+        ptr::drop_in_place(&mut not_a_bool as *mut u8 as *mut bool)
+    };
+}