Language Configuration receives its own topic: https://vscode-ext-docs.azurewebsites.net/api/language-extensions/language-configuration-guide

Previously it was at: https://code.visualstudio.com/docs/extensionAPI/extension-points#_contributeslanguages

I want someone familiar with the features to do a fact check and edit for this topic, so I'm choosing @rebornix .

• Like the other sections, please write up Word Pattern and Indentation Rules
  • Make edits in the code at: https://github.com/Microsoft/vscode-extension-samples/blob/master/language-configuration-sample/language-configuration.json
  • Make edits in the guide at: https://github.com/Microsoft/vscode-docs/blob/ext-docs/api/language-extensions/language-configuration-guide.md
  • Update the JSON hover message for wordPattern. Currently it's very vague what it does as in: The word definition for the language.

For @octref:

• Make contributes.languages point to this guide, instead of listing everything