Add a NEWS document

Uses Clearance's as a reference: https://github.com/thoughtbot/clearance/blob/master/NEWS.md

NEWS.md

@@ -0,0 +1,71 @@
+# News
+
+The noteworthy changes for each Bourbon version are included here. For a
+complete changelog, see the Git history for each version via the version links.
+
+## `master`
+
+### Added
+
+- Added a `contrast-switch` mixin that switches between two colors based on the
+  lightness of a another color. Great for building button styles.
+- Added an `$all-text-inputs-invalid` variable to target the `:invalid`
+  pseudo-class on all text-based inputs.
+- The `ellipsis` mixin now takes a `$display` argument.
+- Added a font stack for system fonts: `$font-stack-system`.
+- Added a `hide-visually` mixin that hides an element visually while still
+  allowing the content to be accessible to assistive technology,
+  e.g. screen readers.
+- The `font-face` mixin now allows additional CSS properties to be included in
+  its block, which will output as part of the `@font-face` declaration.
+  See [2356719].
+
+### Changed
+
+- The global default for the `modular-scale` ratio is now set to
+  `$major-third` (`1.25`), instead of `$perfect-fourth` (`1.333`).
+- All font stack variables are now prefixed with `$font-stack-`,
+  e.g. `$font-stack-helvetica`.
+- Global settings are now set via a `$bourbon` map, instead of variables.
+  See [4e43c2d].
+- The `clearfix` mixin now uses `block` display, instead of `table`.
+
+### Deprecated
+
+- The `$weight` and `$style` arguments in the `font-face` mixin have been
+  deprecated. Instead, you can now include these—along with other CSS
+  properties—within the mixin block and they’ll be output as part of the
+  `@font-face` declaration.
+
+[2356719]: https://github.com/thoughtbot/bourbon/commit/235671948ef3a9c343c4391d250082a0373c8d83
+[4e43c2d]: https://github.com/thoughtbot/bourbon/commit/4e43c2d7507999b539771bdc1b3733b18b3c1883
+
+## [5.0.0.alpha.0] - August 21, 2015
+
+### Added
+
+- Added a `$global-font-file-formats` setting to globally set the file formats
+  for the `font-face` mixin. The default is `("ttf", "woff2", "woff")`.
+
+### Changed
+
+- Removed the type selectors in `$all-text-inputs` and `$all-buttons` to
+  reduce specificity.
+- Font stacks have been modernized.
+- The `strip-units` function is now `strip-unit`.
+- The `size` mixin now requires a comma-separated argument list,
+  e.g. `@include size(1em, 2em);`.
+
+### Deprecated
+
+- All vendor prefixing mixins have been deprecated. We recommend using a more
+  robust and maintainable solution
+  like [Autoprefixer](https://github.com/postcss/autoprefixer).
+- The `$global-prefixes` setting has been deprecated and the `prefixer` mixin
+  has been refactored and no longer uses it.
+- The `em` and `rem` mixins have been deprecated.
+- The `$monospace` font stack variable has been deprecated in favor of new
+  `$consolas`, `$courier-new` and `$monaco` variables.
+- The `triangle` mixin has been deprecated.
+
+[5.0.0.alpha.0]: https://github.com/thoughtbot/bourbon/compare/v4.2.6...v5.0.0.alpha.0

RELEASING.md

@@ -6,6 +6,8 @@
   - `package.json`
   - `bower.json`
 
+1. Update `NEWS.md`
+
 1. Commit changes. Use the convention “Bourbon vX.X.X” in your commit message.
    There shouldn’t be code changes, and thus CI doesn’t need to run.