Docs: Update links

* Replace links to the Apache Server Configs `doc` directory, as it no
  longer exists: https://github.com/h5bp/server-configs-apache/commit/4f778c4a22da91721bc37c2eb10989b902ac4429.

* Remove link to the `Node build script` repository as the project is
  no longer maintained.

* Update `GitHub - Ignoring files` link.