Mention extension settings in README
## Extension Settings
Include if your extension adds any VS Code settings through the `contributes.configuration` extension point.
For example:
This extension contributes the following settings:
- `myExtension.enable`: enable/disable this extension
- `myExtension.thing`: set to `blah` to do something
Ideally this should be updated every time a configuration / configurability feature / feature with configurability is added to the extension. If there are lot of configurations, some basic and high level overview can be given