Update sample.tslint.json

Seems I didn't update the sample json with the switch-clause setting and typedef change.

A bit unrelated: https://github.com/madskristensen/SchemaStore/blob/master/SchemaStore/schemas/json/tslint.json
I added all the descriptions to schemastore (the schema itself was already there), this way you can get intellisense for tslint.json in Visual Studio. We might want to keep this up to date!