Update README.md

README.md

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 An icosphere creator written in Swift, with a SwiftUI SceneKit view that renders the generated geometries.
 
+## Usage
+
+The ico class generates creates an icosahedron, a  polyhedron with 20 equilateral triangles.
+
+It converts this into a sphere by splitting each triangle into four smaller triangles. 
+
+This process can be repeated to create a smoother sphere.
+
+```swift
+func generateIcoSphere(recursions: Int = 0) 
+```
+
+The core generator returns an Icosphere struct that contains the data for the vertices and indeces of the shape. These can be used to create stranger, irregular geometries.
+
+
+
 
 
 ### sources