Fix mg_http_send_redirect doc

PUBLISHED_FROM=77cd3df9959b0e3a2550d1581586e69878bbee0d

docs/c-api/http_server.h/mg_http_send_redirect.md

@@ -13,12 +13,8 @@ Sends a redirect response.
 new location.
 If `extra_headers` is not empty, then `extra_headers` are also sent
 after the reponse line. `extra_headers` must NOT end end with new line.
+
 Example:
 
-     mg_send_response_line(nc, 200, "Access-Control-Allow-Origin: *");
-
-Will result in:
-
-     HTTP/1.1 200 OK\r\n
-     Access-Control-Allow-Origin: *\r\n 
+     mg_http_send_redirect(nc, 302, mg_mk_str("/login"), mg_mk_str(NULL));