Document limits on static and dynamic linking for HPE NonStop platforms.

Documentation is necessary as static and dynamic linking cause SIGSEGV
during atexit() processing on the platform.

Fixes: 19951

Signed-off-by: Randall S. Becker <randall.becker@nexbridge.ca>

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from #19952)

(cherry picked from commit e80518d)

NOTES-NONSTOP.md

@@ -44,6 +44,20 @@ instead of `nsx` in the set above.
 You cannot build for TNS/E for FIPS, so you must specify the `no-fips`
 option to `./Configure`.
 
+Linking and Loading Considerations
+----------------------------------
+
+Because of how the NonStop Common Runtime Environment (CRE) works, there are
+restrictions on how programs can link and load with OpenSSL libraries.
+On current NonStop platforms, programs cannot both statically link OpenSSL
+libraries and dynamically load OpenSSL shared libraries concurrently. If this
+is done, there is a high probability of encountering a SIGSEGV condition
+relating to `atexit()` processing when a shared library is unloaded and when
+the program terminates. This limitation applies to all OpenSSL shared library
+components.
+
+A resolution to this situation is under investigation.
+
 About Prefix and OpenSSLDir
 ---------------------------