use the correct url in the status

i was trying to see how Go implemented rate limiting, but noticed
that the url in the comments was about tickers.

Author: parasquid

examples/go-by-example-channels/rate-limiting.rb

@@ -7,7 +7,7 @@
 Channel = Concurrent::Channel
 
 ## Go by Example: Rate Limiting
-# https://gobyexample.com/tickers
+# https://gobyexample.com/rate-limiting
 
 requests = Channel.new(buffer: :buffered, capacity: 5)
 (1..5).each do |i|