docs: add changelog and readme updates for env variable support

Co-authored-by: garrytrinder <11563347+garrytrinder@users.noreply.github.com>

Author: Copilot

CHANGELOG.md

@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added:
 
 - Install: Added automated install and upgrade support for Linux using official setup scripts
+- Setting: Added `env` setting to pass environment variables when starting Dev Proxy
+- Task provider: Added `env` property to task definition for passing environment variables
 - Quick Fixes: Enable local language model fix now adds or updates `languageModel.enabled: true` for supported plugins only
 - Workspace: Added automatic prompt to recommend extension in `.vscode/extensions.json` when Dev Proxy config files are detected
 - Command: Added `Add to Workspace Recommendations` to manually add extension to workspace recommendations