README.md in acme-client-0.2.4 vs README.md in acme-client-0.3.0

@@ -83,17 +83,21 @@
 # Start a webserver, using your shiny new certificate
 # ruby -r openssl -r webrick -r 'webrick/https' -e "s = WEBrick::HTTPServer.new(
 #   :Port => 8443,
 #   :DocumentRoot => Dir.pwd,
 #   :SSLEnable => true,
-#   :SSLPrivateKey => OpenSSL::PKey::RSA.new( File.read('key.pem') ),
+#   :SSLPrivateKey => OpenSSL::PKey::RSA.new( File.read('privkey.pem') ),
 #   :SSLCertificate => OpenSSL::X509::Certificate.new( File.read('cert.pem') )); trap('INT') { s.shutdown }; s.start"
 ```
 
 # Not implemented
 
 - Recovery methods are not implemented.
 - proofOfPossession-01 is not implemented.
+
+# Requirements
+
+Ruby >= 2.1
 
 ## Development
 
 All the tests use VCR to mock the interaction with the server but if you
 need to record new interation against the server simply clone boulder and