A note about key encapsulation/decapsulation support in OpenSSL

Related: open-quantum-safe#485
Signed-off-by: Dmitry Belyavskiy <[email protected]>

README.md

@@ -144,6 +144,13 @@ Also not fully supported in 3.0.2 is performance testing as per the openssl
 These versions have full support for all TLS1.3 operations using PQ algorithms
 when deploying `oqsprovider`.
 
+## 3.4 and greater
+
+These version are expected to support the `openssl pkeyutl -encap/-decap`
+syntax for testing key encapsulation and decapsulation for test purposes. To
+use this option, OQS provider should be built with KEM encoding/decoding
+support.
+
 ## All versions
 
 A limitation present in older OpenSSL versions is the number of default groups