document vscode extension install options

vscode-extension/README.md

@@ -11,6 +11,28 @@ VS Code extension with buttons for `epm-docker-test.sh`.
 
 The extension runs commands in a normal VS Code terminal, so the same output and prompts remain visible.
 
+## Install
+
+For day-to-day local use without packaging:
+
+```bash
+mkdir -p ~/.vscode/extensions/eter.epm-docker-test-runner-0.1.0
+rsync -a --delete ./ ~/.vscode/extensions/eter.epm-docker-test-runner-0.1.0/
+```
+
+Then run `Developer: Reload Window` in VS Code.
+
+To install as a VSIX package:
+
+```bash
+cd vscode-extension
+npm install -g @vscode/vsce
+vsce package
+code --install-extension epm-docker-test-runner-0.1.0.vsix
+```
+
+The same VSIX can be installed from the VS Code command `Extensions: Install from VSIX...`.
+
 ## Actions
 
 - `Run app on systems`: asks for an app and target systems.