Update changelog since v2.1.1 (#28)

Author: thomashoneyman

CHANGELOG.md

@@ -5,24 +5,28 @@ Notable changes to this project are documented in this file. The format is based
 ## [Unreleased]
 
 Breaking changes:
+- Added support for PureScript 0.14 and dropped support for all previous versions (#24)
 
 New features:
+- Added `imul` (#18)
 
 Bugfixes:
 
 Other improvements:
+- Migrated CI to GitHub Actions and updated installation instructions to use Spago (#26)
+- Added a changelog and pull request template (#27)
 
 ## [v2.1.1](https://github.com/purescript/purescript-math/releases/tag/v2.1.1) - 2018-05-22
 
-Relicensed as BSD3
+- Relicensed as BSD3
 
 ## [v2.1.0](https://github.com/purescript/purescript-math/releases/tag/v2.1.0) - 2017-06-25
 
-Add `τ` constant (@FranklinChen)
+- Added `τ` constant (@FranklinChen)
 
 ## [v2.0.0](https://github.com/purescript/purescript-math/releases/tag/v2.0.0) - 2016-06-04
 
-This release is intended for the PureScript 0.9.1 compiler and newer.
+- This release is intended for the PureScript 0.9.1 compiler and newer.
 
 ## [v2.0.0-rc.1](https://github.com/purescript/purescript-math/releases/tag/v2.0.0-rc.1) - 2016-05-20
 
@@ -35,13 +39,12 @@ This release is intended for the PureScript 0.9.1 compiler and newer.
 
 ## [v0.2.0](https://github.com/purescript/purescript-math/releases/tag/v0.2.0) - 2015-06-30
 
-This release works with versions 0.7.\* of the PureScript compiler. It will not work with older versions. If you are using an older version, you should require an older, compatible version of this library.
+- This release works with versions 0.7.\* of the PureScript compiler. It will not work with older versions. If you are using an older version, you should require an older, compatible version of this library.
 
 ## [v0.1.1](https://github.com/purescript/purescript-math/releases/tag/v0.1.1) - 2015-03-22
 
-Updated docs
+- Updated docs
 
 ## [v0.1.0](https://github.com/purescript/purescript-math/releases/tag/v0.1.0) - 2014-04-25
 
-
-
+- Initial versioned release