Add API Docs

api/README.md

@@ -35,3 +35,20 @@ export async function activate() {
 }
 ```
 
+## Full API reference
+
+📘 **[Python Environments API reference](https://github.com/microsoft/vscode-python-environments/blob/main/docs/README.md)**
+
+The complete manual documents every method and data type, organized by domain -
+environments, packages, projects, execution, environment variables, and
+extensibility - with field tables, parameter tables, return types, and examples.
+
+- [Environments](https://github.com/microsoft/vscode-python-environments/blob/main/docs/README.md#environments) - discover, resolve, select, create, and remove interpreters
+- [Packages](https://github.com/microsoft/vscode-python-environments/blob/main/docs/README.md#packages) - list, install, uninstall, and look up versions
+- [Projects](https://github.com/microsoft/vscode-python-environments/blob/main/docs/README.md#projects) - the folders the extension tracks
+- [Execution](https://github.com/microsoft/vscode-python-environments/blob/main/docs/README.md#execution) - run Python in terminals, tasks, and background processes
+- [Environment variables](https://github.com/microsoft/vscode-python-environments/blob/main/docs/README.md#environment-variables) - resolved variables for a scope
+- [Extensibility](https://github.com/microsoft/vscode-python-environments/blob/main/docs/README.md#extensibility) - register your own environment manager, package manager, or project creator
+
+See [`CHANGELOG.md`](https://github.com/microsoft/vscode-python-environments/blob/main/api/CHANGELOG.md) for API changes between versions.
+