Apply suggestions from code review

Co-authored-by: Fabien Potencier <fabien@potencier.org>

Author: bobvandevijver

messenger.rst

@@ -744,11 +744,11 @@ running the ``messenger:consume`` command.
 .. _messenger-retries-failures:
 
 Rate limited transport
-~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~
 
 Sometimes you might need to rate limit your message worker. You can configure a
-rate limiter on transport (requires the :doc:`RateLimiter component </rate-limiter>`)
-by setting its ``rate_limiter`` option.
+rate limiter on a transport (requires the :doc:`RateLimiter component </rate-limiter>`)
+by setting its ``rate_limiter`` option:
 
 .. configuration-block::