Update README file

Signed-off-by: Simo Sorce <[email protected]>

README.md

@@ -1,10 +1,10 @@
 [![Build](https://github.com/latchset/pkcs11-provider/actions/workflows/build.yml/badge.svg)](https://github.com/latchset/pkcs11-provider/actions/workflows/build.yml)
 
 This is an Openssl 3.x provider to access Hardware or Software Tokens
-using the PKCS#11 Cryptographic Token Interface
+using the PKCS#11 Cryptographic Token Interface.
 
-This code targets version 3.1 of the interface but should be backwards
-compatible to previous versions as well.
+This code targets PKCS#11 version 3.1 but is backwards compatible to
+version 3.0 and 2.40 as well.
 
 Spec:
 https://docs.oasis-open.org/pkcs11/pkcs11-spec/v3.1/pkcs11-spec-v3.1.html