Add docs badges (#196)

README.md

@@ -4,6 +4,8 @@
 [![AdvancedHMC-CI](https://github.com/TuringLang/AdvancedHMC.jl/workflows/AdvancedHMC-CI/badge.svg?branch=master)](https://github.com/TuringLang/AdvancedHMC.jl/actions?query=workflow%3AAdvancedHMC-CI)
 [![DOI](https://zenodo.org/badge/72657907.svg)](https://zenodo.org/badge/latestdoi/72657907)
 [![Coverage Status](https://coveralls.io/repos/github/TuringLang/AdvancedHMC.jl/badge.svg?branch=kx%2Fbug-fix)](https://coveralls.io/github/TuringLang/AdvancedHMC.jl?branch=kx%2Fbug-fix)
+[![Stable](https://img.shields.io/badge/docs-stable-blue.svg)](https://turing.ml/stable/docs/library/advancedhmc/)
+[![Dev](https://img.shields.io/badge/docs-dev-blue.svg)](https://turing.ml/dev/docs/library/advancedhmc/)
 
 AdvancedHMC.jl provides a robust, modular and efficient implementation of advanced HMC algorithms. An illustrative example for AdvancedHMC's usage is given below. AdvancedHMC.jl is part of [Turing.jl](https://github.com/TuringLang/Turing.jl), a probabilistic programming library in Julia. 
 If you are interested in using AdvancedHMC.jl through a probabilistic programming language, please check it out!