Release 0.21.0

Also, standardize the changelog to the https://keepachangelog.com
format.

CHANGELOG.md

@@ -1,21 +1,26 @@
-# Change log
+# Changelog
 
-## master (unreleased)
+## Unreleased
 
-### 0.20.0 (2020-07-30)
+## 0.21.0 (2020-08-19)
+### Fixed
+- Fix broken `pry` commands like `ls`. ([@jamesfischer8][])
 
-- Fix `up` and `down` commands in `pry`. ([@gsamokovarov][])
+## 0.20.0 (2020-07-30)
+### Added
 - Support for `pry-remote`. ([@gsamokovarov][])
+### Fixed
+- Fix `up` and `down` commands in `pry`. ([@gsamokovarov][])
 
-### 0.12.0 (2020-07-17)
-
+## 0.12.0 (2020-07-17)
+### Added
 - Support for `pry` version `0.13` and above. ([@gsamokovarov][])
+### Fixed
 - Fix a crash in multi-threaded environments. ([@gsamokovarov][])
 
 ## 0.11.0 (2020-02-08)
-
-### Changes
-
+### Changed
 - Requiring `pry` before `break` is no longer a prerequisite for automatic Pry integration. ([@gsamokovarov][])
 
 [@gsamokovarov]: https://github.com/gsamokovarov
+[@jamesfischer8]: https://github.com/jamesfischer8