Refer to RFCs consistently.

We were a mix of "RFC1234" and "RFC 1234". Apparently there is actually
an answer for this, which is with a space textually and without a space
in the citation/reference tag:
https://datatracker.ietf.org/doc/html/rfc7322#section-3.5

Change-Id: I0c44023163fe3a2a3ffe28cbc644d4c952dc8f1e
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48965
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/util/fetch_ech_config_list.go b/util/fetch_ech_config_list.go
index 03b2f87..badaae2 100644
--- a/util/fetch_ech_config_list.go
+++ b/util/fetch_ech_config_list.go
@@ -175,7 +175,7 @@
 		// Verify that this response answers the question that we asked in the
 		// query. If the resolver encountered any CNAMEs, it's not guaranteed
 		// that the response will contain a question with the same QNAME as our
-		// query. However, RFC8499 Section 4 indicates that in general use, the
+		// query. However, RFC 8499 Section 4 indicates that in general use, the
 		// response's QNAME should match the query, so we will make that
 		// assumption.
 		q, err := p.Question()