feat: update usage instructions

Author: koderzi

README.md

@@ -18,3 +18,18 @@ To use this repository, follow the steps below:
 
 1. Create new repository by clicking the Use this template button above.
 2. Open your duplicated repository in VSCode using the command ">Dev Containers: Clone Repositories in Named Container Volume". You can name your container for easy referencing.
+
+## mise and py-init
+
+This devcontainer uses "mise" (a small environment/tool manager) and a convenience shell helper named `py-init` to quickly create a mise-managed Python environment and a project virtualenv.
+
+Quick usage
+- Open a new shell and cd into your project directory.
+- Run:
+  - py-init 3.11
+  - or any supported version (e.g. py-init 3.10, py-init 3.13)
+
+What py-init does
+- Creates/updates a local mise.toml in the current directory.
+- Uses mise to select the requested Python version.
+- Configures the local virtualenv path to .venv and enables automatic creation.