Update README.md

Author: ChrisRackauckas

README.md

@@ -1,6 +1,6 @@
 # LinearSolvers
 
-[![Stable](https://img.shields.io/badge/docs-stable-blue.svg)](http://linearsolve.sciml.ai/stale)
+[![Stable](https://img.shields.io/badge/docs-stable-blue.svg)](http://linearsolve.sciml.ai/stable)
 [![Dev](https://img.shields.io/badge/docs-dev-blue.svg)](http://linearsolve.sciml.ai/dev)
 [![Build Status](https://github.com/SciML/LinearSolvers.jl/workflows/CI/badge.svg)](https://github.com/SciML/LinearSolvers.jl/actions)
 [![Coverage](https://codecov.io/gh/SciML/LinearSolvers.jl/branch/master/graph/badge.svg)](https://codecov.io/gh/SciML/LinearSolvers.jl)