fix documentation badges

Author: visr

README.md

@@ -3,7 +3,9 @@
 [![Build Status](https://ci.appveyor.com/api/projects/status/github/SimonDanisch/GeometryBasics.jl?svg=true)](https://ci.appveyor.com/project/SimonDanisch/GeometryBasics-jl)
 [![Codecov](https://codecov.io/gh/JuliaGeometry/GeometryBasics.jl/branch/master/graph/badge.svg)](https://codecov.io/gh/SimonDanisch/GeometryBasics.jl)
 
-**Documentation**: [![][https://img.shields.io/badge/docs-stable-lightgrey.svg]][http://juliageometry.github.io/GeometryBasics.jl/stable/] [![][https://img.shields.io/badge/docs-dev-blue.svg]][http://juliageometry.github.io/GeometryBasics.jl/dev]
+**Documentation**:
+[![Docs - stable](https://img.shields.io/badge/docs-stable-lightgrey.svg)](http://juliageometry.github.io/GeometryBasics.jl/stable/)
+[![Docs - dev](https://img.shields.io/badge/docs-dev-blue.svg)](http://juliageometry.github.io/GeometryBasics.jl/dev)
 
 # GeometryBasics.jl