update index.md in docs

Author: vlandau

docs/src/index.md

@@ -1,11 +1,11 @@
 # SpatialGraphs.jl
 
-SpatialGraphs.jl introduces the `AbstractSpatialGraph`. `AbstractSpatialGraphs` 
+SpatialGraphs.jl introduces the `AbstractSpatialGraph`. An `AbstractSptialGraph` is an `AbstractGraph`
 are a subtype of `Graphs.AbstractGraph`, and can be weighted or directed.
-SpatialGraphs.jl is useful for turning spatial data into graphs. This can be
-useful for landscape connectivity analysis, hydrology, and other spatial
-network processes. AbstractSpatialGraphs are AbstractGraphs, so methods from 
-Graphs.jl work right out of the box. Go to [Graph Types](@ref graph_types) 
+SpatialGraphs.jl turns spatial data into graphs, which enables users to leverage the vast
+functionality of Graphs.jl to analyze landscape connectivity, hydrology, and other spatial
+network processes. This package implements the Graphs.jl interface, so methods
+from Graphs.jl work right out of the box. Go to [Graph Types](@ref graph_types) 
 for more details on the graph types implemented in this package.
 
 ### Table of Contents