Add CHANGELOG entry

Author: NickColley

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- Enable support for Node.js version 12/13 by upgrading to [node-sass v4.13.0](https://github.com/sass/node-sass/releases/tag/v4.13.0) - thanks [@nickcolley](https://github.com/nickcolley).
+
 ## [v1.6.0](https://github.com/stevenschobert/metalsmith-sass/releases/tag/v1.6.0)
 
 _01/20/2018_
@@ -43,7 +47,7 @@ _06/08/2015_
 _05/25/2015_
 
 - Updated to [node-sass v3.0](https://github.com/sass/node-sass/releases/tag/v3.0.0) :tada:
-- Added support for [source maps](https://github.com/stevenschobert/metalsmith-sass/blob/b162dd7c6ae6e5c6ee858e4db7bfc2a5c6393a85/README.md#source-maps).
+- Added support for [source maps](https://github.com/stevenschobert/metalsmith-sass/blob/b162dd7c6ae6e5c6ee858e4db7bfc2a5c6393a85/README.md#source-maps).
 - All options now get passed through to node-sass (no more manual updates for new options!)
 
 ## [v0.7.0](https://github.com/stevenschobert/metalsmith-sass/releases/tag/v0.7.0)
@@ -78,7 +82,7 @@ _10/17/2014_
 
 This release updates [libsass](https://github.com/sass/libsass/) (the underlying sass library) to [v3.0](https://github.com/sass/libsass/releases/tag/3.0), which includes **tons** of major fixes and improvements.
 
-##### Check out the [Libsass v3.0 release notes](https://github.com/sass/libsass/releases/tag/3.0) for a detailed list of updates.
+##### Check out the [Libsass v3.0 release notes](https://github.com/sass/libsass/releases/tag/3.0) for a detailed list of updates.
 
 ---
 
@@ -109,4 +113,3 @@ _06/09/2014_
 
 - Partials are now properly ignored (thanks [@dpisklov](https://github.com/dpisklov)!). Addresses #1 and #2.
 - Added an `outputDir` option. Can be used in combination with `Metalsmith.destination()` to control output paths for stylesheets.
-