Tweak notes about supported versions.

Author: anthony-tuininga

README.md

@@ -7,12 +7,11 @@ of exclusions.  See the
 [homepage](https://oracle.github.io/python-cx_Oracle/index.html) for a
 feature list.
 
-cx_Oracle 7 has been tested with Python version 2.7, and with versions
-3.5 and higher. You can use cx_Oracle with Oracle 11.2 and higher client
-libraries (including Oracle 18.3). Oracle's standard client-server version
-interoperability allows connection to both older and newer databases,
-for example Oracle 18.3 client libraries can connect to Oracle
-Database 11.2.
+cx_Oracle 7 has been tested with Python version 2.7, and with versions 3.5
+through 3.8. You can use cx_Oracle with Oracle 11.2, 12.1 and 12.2, 18c and 19c
+client libraries. Oracle's standard client-server version interoperability
+allows connection to both older and newer databases. For example Oracle 19c
+client libraries can connect to Oracle Database 11.2.
 
 ## Installation