http: use right PR number

Author: ShogunPanda

doc/api/http.md

@@ -1449,7 +1449,7 @@ type other than {net.Socket}.
 added: v0.1.90
 changes:
   - version: REPLACEME
-    pr-url: https://github.com/nodejs/node/pull/42811
+    pr-url: https://github.com/nodejs/node/pull/42812
     description: The `options` argument is now supported.
 -->