doc: fix commit guideline url

PR-URL: https://github.com/nodejs/node/pull/12862
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

.github/PULL_REQUEST_TEMPLATE.md

@@ -13,7 +13,7 @@ Contributors guide: https://github.com/nodejs/node/blob/master/CONTRIBUTING.md
 - [ ] `make -j4 test` (UNIX), or `vcbuild test` (Windows) passes
 - [ ] tests and/or benchmarks are included
 - [ ] documentation is changed or added
-- [ ] commit message follows [commit guidelines](https://github.com/nodejs/node/blob/master/CONTRIBUTING.md#commit-guidelines)
+- [ ] commit message follows [commit guidelines](https://github.com/nodejs/node/blob/master/CONTRIBUTING.md#commit-message-guidelines)
 
 ##### Affected core subsystem(s)
 <!-- Provide affected core subsystem(s) (like doc, cluster, crypto, etc). -->