doc: fix typo in http2.md

Backport-PR-URL: #20456
PR-URL: #18872
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

doc/api/http2.md

@@ -1761,7 +1761,7 @@ changes:
     Http2ServerRequest class to use.
     Useful for extending the original `Http2ServerRequest`.
     **Default:** `Http2ServerRequest`
-  * `Http2ServerResponse` {htt2.Http2ServerResponse} Specifies the
+  * `Http2ServerResponse` {http2.Http2ServerResponse} Specifies the
     Http2ServerResponse class to use.
     Useful for extending the original `Http2ServerResponse`.
     **Default:** `Http2ServerResponse`