READMEs: add note about 5.0 status (#11355)

1 files changed, 20 insertions, 0 deletions

diff --git a/README.adoc b/README.adoc
index 4da813b9c8..3c361cd8ce 100644
--- a/README.adoc
+++ b/README.adoc
@@ -1,3 +1,23 @@
+=== ⚠️ CAUTION
+
+The developer team is currently preparing the release of OCaml 5.0. This release
+sports a full rewrite of its runtime system for shared-memory parallel
+programming using domains and native support for concurrent programming using
+effect handlers.
+
+Owing to the large number of changes, the initial 5.0 release will be more
+experimental than usual.  It is recommended that all users wanting a stable
+release use the 4.14 release which will continue to be supported and updated
+while 5.0 reaches feature and stability parity. Similarly, if you need one of
+the ports not yet supported in the 5.0 release you must use the 4.14 release.
+
+The initial release of OCaml 5.0 will only support the native compiler under
+ARM64 and x86-64 architectures under Linux and macOS. On Windows, only the
+Mingw-w64 port is supported.  Support for other 64-bit architectures and systems
+will be added back in later releases. On 32-bit systems, only the bytecode
+compiler is supported.  Native-code support for these systems is under
+discussion.
+
 |=====
 | Branch `trunk` | Branch `4.14` | Branch `4.13` | Branch `4.12`