Update draft-ietf-quic-ack-frequency.md

Co-authored-by: Lucas Pardue <lucas@lucaspardue.com>

draft-ietf-quic-ack-frequency.md

@@ -163,7 +163,7 @@ endpoint performance in the following ways:
  opportunities available to other flows sharing the same link.
 
 
-However, As discussed in {{implementation}}, a unilateral reduction in
+However, as discussed in {{implementation}}, a unilateral reduction in
 acknowledgement frequency can lead to undesirable consequences for congestion
 control and loss recovery.