docs: link to the typescript-tools spec

Author: EricCrosson

README.md

@@ -11,7 +11,9 @@
 [semantic-release]: https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg
 
 The `typescript-tools` are an opinionated collection of utilities for working with
-TypeScript monorepos.
+TypeScript monorepos. Read more in the [typescript-tools spec].
+
+[typescript-tools spec]: https://github.com/typescript-tools/spec
 
 ## The Problem