More precisely note status of unstable-apple-new

Author: madsmtm

crates/objc2/Cargo.toml

@@ -65,7 +65,7 @@ unstable-c-unwind = []
 # For better documentation on docs.rs
 unstable-docsrs = []
 
-# Enable new features available on ARM64 on:
+# Enable some new features available on ARM64 on:
 # - macOS 13.0
 # - iOS 16.0
 # - tvOS 16.0
@@ -74,7 +74,9 @@ unstable-docsrs = []
 # See https://developer.apple.com/videos/play/wwdc2022/110363/ for an overview
 # of the features.
 #
-# Currently untested.
+# Currently untested, might be unsound or lead to confusing compiler errors.
+#
+# Additionally, the message sending improvements is not yet implemented.
 unstable-apple-new = ["apple"]
 
 # Runtime selection. See `objc-sys` for details.