Update changelog to a keepachangelog format (#594)

Author: glensc

CHANGELOG.md

@@ -1,41 +1,49 @@
-CHANGE LOG
-==========
+# Changelog
 
+All notable changes to this project will be documented in this file.
 
-## 10.1.1 (26/10/2020)
+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).
+
+## [10.1.1] - 2020-10-26
 
 * Fixed phpdoc typo
 * Fixed broken query builder
 
+[10.1.1]: https://github.com/GitLabPHP/Client/compare/10.1.0...10.1.1
 
-## 10.1.0 (24/10/2020)
+## [10.1.0] - 2020-10-24
 
 * Added method to get protected branches for a project
 * Added with_merge_status_recheck option for fetching MRs
 * Added commit cherry-pick API
 * Added support for optional Note parameters 
 * Deprecated models API
 
+[10.1.0]: https://github.com/GitLabPHP/Client/compare/10.0.1...10.1.0
 
-## 10.0.1 (24/10/2020)
+## [10.0.1] - 2020-10-24
 
 * Fixed using the name of a group as an ID
 * Fixed various phpdoc issues
 * Reverted query builder changes
 
+[10.0.1]: https://github.com/GitLabPHP/Client/compare/10.0.0...10.0.1
 
-## 10.0.0 (15/08/2020)
+## [10.0.0] - 2020-08-15
 
 * Added void return types to void methods
 
+[10.0.0]: https://github.com/GitLabPHP/Client/compare/10.0.0-RC2...10.0.0
 
-## 10.0.0-RC2 (23/07/2020)
+## [10.0.0-RC2] - 2020-07-23
 
 * Restored 9.x behaviour for empty JSON responses
 * Support the issue link link_type parameter
 
+[10.0.0-RC2]: https://github.com/GitLabPHP/Client/compare/10.0.0-RC1...10.0.0-RC2
 
-## 10.0.0-RC1 (22/07/2020)
+## [10.0.0-RC1] - 2020-07-22
 
 * Removed all deprecated functionality
 * Switched to PSR-17 and PSR-18
@@ -46,14 +54,16 @@ CHANGE LOG
 * Added scalar param types
 * Added user events API
 
+[10.0.0-RC1]: https://github.com/GitLabPHP/Client/compare/9.18.1...10.0.0-RC1
 
-## 9.18.1 (22/07/2020)
+## [9.18.1] - 2020-07-22
 
 * Fixed error in getHeader function
 * Fixed incorrect param type doc
 
+[9.18.1]: https://github.com/GitLabPHP/Client/compare/9.18.0...9.18.1
 
-## 9.18.0 (11/07/2020)
+## [9.18.0] - 2020-07-11
 
 * Deprecated all APIs that are deprecated or removed as of GitLab 13.1
 * Deprecated old authentication methods and deprecated not specifying an authentication mode
@@ -73,18 +83,22 @@ CHANGE LOG
 * Allow to search and find issues by "assignee_id"
 * Updated Issues to support updated_after
 
+[9.18.0]: https://github.com/GitLabPHP/Client/compare/9.17.1...9.18.0
 
-## 9.17.1 (17/02/2020)
+## [9.17.1] - 2020-02-17
 
 * Fixed text encoding for `Repositories::createCommit()`
 * Corrected lots of phpdoc errors and edges cases
 
+[9.17.1]: https://github.com/GitLabPHP/Client/compare/9.17.0...9.17.1
 
-## 9.17.0 (17/02/2020)
+## [9.17.0] - 2020-02-17
 
 * Added support for the wiki APIs
 * Implemented `Environments::show()`
 * Implemented `Issues::showParticipants()`
 * Add method to get issues for a group
 * Add forks API call to return all forked projects
 * Added users projects request parameters normalization
+
+[9.17.0]: https://github.com/GitLabPHP/Client/compare/9.16.0...9.17.0