The current content of https://vscode-ext-docs.azurewebsites.net/api/references/principle-and-patterns is a hodgepodge, addressing a wide range of audiences:

• Some contents are very basic for beginners, like "Using Node.js modules with Extensions".
• Some content are for every extension developers, like "No access to DOM", "Extension Isolation / Stability"
• Some contents are for API readers, like "Pormises", "Cancellation Tokens", etc

We should split these contents into meaningful places. For example:

• Some content can go to a new topic "Advanced Topics / Extension Host" that explains the extension host runtime
• Some content can become a top section of https://vscode-ext-docs.azurewebsites.net/api/references/vscode-api