API Interactive renderer communication is not in stable

The documentation for `Interactive Notebooks` here https://code.visualstudio.com/api/extension-guides/notebook#interactive-notebooks Is only applicable for proposed API, hence not sure it should be in the documentation. To my knowledge we only document stable API. the `rendererScripts` is only available in proposed API. ``` you might modify your controller rendererScripts to refere ``` ```typescript this._controller.rendererScripts.push( new vscode.NotebookRendererScript( vscode.Uri.file(/* path to script */), rendererScriptId ) ); ``` @connor4312 @roblourens /cc