docs: remove link to missing section

closes expressjs#3179

Author: stz-seongheon

Security.md

@@ -5,7 +5,6 @@ project.
 
   * [Reporting a Bug](#reporting-a-bug)
   * [Disclosure Policy](#disclosure-policy)
-  * [Receiving Security Updates](#receiving-security-updates)
   * [Comments on this Policy](#comments-on-this-policy)
 
 ## Reporting a Bug