update README

with a one-liner description

Author: yeesian

README.md

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 # LibSpatialIndex
 
-[![Build Status](https://travis-ci.org/JuliaGeo/LibSpatialIndex.jl.svg?branch=master)](https://travis-ci.org/JuliaGeo/LibSpatialIndex.jl)
+[![Build Status](https://travis-ci.org/JuliaGeo/LibSpatialIndex.jl.svg?branch=master)](https://travis-ci.org/JuliaGeo/LibSpatialIndex.jl) [![Coverage Status](https://coveralls.io/repos/github/JuliaGeo/LibSpatialIndex.jl/badge.svg?branch=master&service=github)](https://coveralls.io/github/JuliaGeo/LibSpatialIndex.jl?branch=master)
 
-[![Coverage Status](https://coveralls.io/repos/github/JuliaGeo/LibSpatialIndex.jl/badge.svg?branch=master&service=github)](https://coveralls.io/github/JuliaGeo/LibSpatialIndex.jl?branch=master)
-
-[![codecov.io](https://codecov.io/github/JuliaGeo/LibSpatialIndex.jl/branch/master/graph/badge.svg)](https://codecov.io/github/JuliaGeo/LibSpatialIndex.jl?branch=master)
+LibSpatialIndex.jl is a julia wrapper around the C API of [libspatialindex](https://github.com/libspatialindex/libspatialindex), for spatially indexing kD bounding box data.
 
 # Quick Guide