Generate changelog and add PR template (#44)

* Generate CHANGELOG.md file using notes from previous GH releases

* Add pull request template

Author: JordanMartinez

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,12 @@
+**Description of the change**
+
+Clearly and concisely describe the purpose of the pull request. If this PR relates to an existing issue or change proposal, please link to it. Include any other background context that would help reviewers understand the motivation for this PR.
+
+---
+
+**Checklist:**
+
+- [ ] Added the change to the changelog's "Unreleased" section with a reference to this PR (e.g. "- Made a change (#0000)")
+- [ ] Linked any existing issues or proposals that this pull request should close
+- [ ] Updated or added relevant documentation
+- [ ] Added a test for the contribution (if applicable)

CHANGELOG.md

@@ -0,0 +1,48 @@
+# Changelog
+
+Notable changes to this project are documented in this file. The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+Breaking changes:
+
+New features:
+
+Bugfixes:
+
+Other improvements:
+
+## [v1.6.1](https://github.com/purescript/purescript-ordered-collections/releases/tag/v1.6.1) - 2019-04-12
+
+* Fix doc comments for `Data.Map.toUnfoldableUnordered` (@bernhard-herzog)
+* Fix a syntax issue in preparation for upcoming parser changes in PureScript v0.13.0 (@natefaubion)
+
+## [v1.6.0](https://github.com/purescript/purescript-ordered-collections/releases/tag/v1.6.0) - 2019-02-14
+
+Added `intersection` and `intersectionWith` for `Map` (@karshan)
+
+## [v1.5.0](https://github.com/purescript/purescript-ordered-collections/releases/tag/v1.5.0) - 2019-02-07
+
+Added `insertWith` for `Map`
+
+## [v1.4.0](https://github.com/purescript/purescript-ordered-collections/releases/tag/v1.4.0) - 2018-10-05
+
+- Added `fromFoldableWithIndex` for `Map`
+
+## [v1.3.0](https://github.com/purescript/purescript-ordered-collections/releases/tag/v1.3.0) - 2018-10-05
+
+- Added `mapMaybe` functions for all types
+- Added `filter` for `Set` types
+
+## [v1.2.0](https://github.com/purescript/purescript-ordered-collections/releases/tag/v1.2.0) - 2018-10-04
+
+- Added `difference` for `Map` (@mschristiansen)
+
+## [v1.1.0](https://github.com/purescript/purescript-ordered-collections/releases/tag/v1.1.0) - 2018-09-06
+
+- Added `NonEmptySet`
+
+## [v1.0.0](https://github.com/purescript/purescript-ordered-collections/releases/tag/v1.0.0) - 2018-05-24
+
+Initial release
+