Update README.md

Author: cdimascio

README.md

@@ -35,8 +35,8 @@
 ```shell
 npm install express-openapi-validator
 
-# experimental OAS 3.1 in alpha (contributions welcome - see branch `oas-3.1` and pr-882)
-npm install express-openapi-validator@6.0.0-alpha.2
+# experimental OAS 3.1 in alpha (contributions welcome - see branch `oas-3.1` and pr-882 (issue-573)
+npm install express-openapi-validator@6.0.0-alpha.3
 ```
 
 ## Usage