[ruby/net-http] Enhanced RDoc for Net::HTTPHeader

https://github.com/ruby/net-http/commit/0af9fb94a9

lib/net/http/header.rb

@@ -513,7 +513,7 @@ module Net::HTTPHeader
     r
   end
 
-  n range= set_range
+  alias range= set_range
 
   # Returns an Integer object which represents the HTTP Content-Length:
   # header field, or +nil+ if that field was not provided.