[doc] add documentation badge

README.md

@@ -2,6 +2,7 @@
 
 STL to cell-wise triangulation to solve FE problems in [Gridap.jl](https://github.com/gridap/Gridap.jl) through [GridapEmbedded.jl](https://github.com/gridap/GridapEmbedded.jl)
 
+[![doc](https://img.shields.io/badge/docs-stable-blue.svg)](https://gridap.github.io/Gridap.jl/stable) [![](https://img.shields.io/badge/docs-dev-blue.svg)](https://gridap.github.io/STLCutters.jl/dev) |
 [![DOI](https://img.shields.io/badge/DOI-10.1016%2Fj.jcp.2022.111162-blue)](https://doi.org/10.1016/j.jcp.2022.111162)
 [![CI](https://github.com/gridap/STLCutters.jl/workflows/CI/badge.svg)](https://github.com/gridap/STLCutters.jl/actions?query=workflow%3ACI)
 [![codecov](https://codecov.io/gh/gridap/STLCutters.jl/branch/main/graph/badge.svg)](https://codecov.io/gh/gridap/STLCutters.jl)