Add Ownable2Step to the docs (#3836)

Co-authored-by: Francisco <fg@frang.io>

contracts/access/README.adoc

@@ -12,6 +12,8 @@ This directory provides ways to restrict who can access the functions of a contr
 
 {{Ownable}}
 
+{{Ownable2Step}}
+
 {{IAccessControl}}
 
 {{AccessControl}}