docs: update

CHANGELOG.md

@@ -5,6 +5,13 @@ All notable changes to components of this project since 0.5.14 will be documente
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+
+- Flakes install in `nix`
+- Override package manager using `_PR_PACKAGE_MANAGER`
+
 ## [0.6.3] 2024-12-11
 
 ### Added

README.md

@@ -83,6 +83,14 @@ Please follow the instruction for your shell:
 
 </details>
 
+<details>
+	<summary>Environment variable configurations</summary>
+
+> - `_PR_LIB`: Directory of modules, analogous to `PATH`. If not provided, search in `PATH` or compile-time provided value.
+> - `_PR_PACKAGE_MANAGER`: Use defined package manager instead of auto-detecting alphabetically
+
+</details>
+
 You can now **press `F` to Pay Respects**!
 
 ## Installing