docs: adds link to published spec to readme.

Author: atombender

README.md

@@ -1,5 +1,7 @@
 # GROQ specification
 
+👉🏻 **Published versions of the spec can be viewed [here](https://sanity-io.github.io/GROQ/)**.
+
 This is the specification for GROQ (Graph-Relational Object Queries), a query language and execution engine made at [Sanity.io](https://www.sanity.io), for filtering and projecting JSON documents.
 The work started in 2015, and the development of this open standard started in 2019.
 Read the [announcement blog post](https://www.sanity.io/blog/we-re-open-sourcing-groq-a-query-language-for-json-documents) to understand more about the specification process and see the [getting started guide](https://www.sanity.io/docs/data-store/how-queries-work) to learn more about the language itself.