README.md - add 'SSL Connection Support' section

README.md

@@ -29,6 +29,17 @@ $ puma
 Without arguments, puma will look for a rackup (.ru) file in
 working directory called `config.ru`.
 
+## SSL Connection Support
+
+Puma will install/compile with support for ssl sockets, assuming OpenSSL
+development files are installed on the system.
+
+If the system does not have OpenSSL development files installed, Puma will
+install/compile, but it will not allow ssl connections.
+
+If the system has OpenSSL development files installed, but you don't want Puma
+to use ssl connections, set ENV['DISABLE_SSL'] to any value.
+
 ## Frameworks
 
 ### Rails