Add readme

Author: Oleksandr Glagoliev

README.md

@@ -1,2 +1,47 @@
 # FortunesAlgorithm
 
+`FortunesAlgorithm` is a Swift package for building Voronoi diagrams using Steven Fortune's algorithm. Algorithm guarantees `O(n log n)` worst-case running time and uses `O(n)` space.
+
+# Installing
+
+`FortunesAlgorithm` can be installed as any other Swift package. Add the following to the `dependencies` section of your `Package.swift`:
+
+```
+.package(url: "https://github.com/fewlinesofcode/FortunesAlgorithm", from: "1.0.0")
+```
+
+# Basic Usage
+
+1. Add package dependency
+2. Import `import FortunesAlgorithm`
+3. Add diagram computation code in appropriate place: 
+
+```
+let fortuneSweep = FortunesAlgorithm()
+var diagram = Diagram()
+let clippingRect = Rectangle(
+            origin: Vertex(x: 20, y: 20),
+            size: Size(width: 100, height: 100)
+        )
+var sites = Set<Site>([Site(x: 10, y: 10), Site(x: 50, y: 50)/* Generate sites you need ... */])
+fortuneSweep.compute(
+            sites: sites,
+            diagram: &diagram,
+            clippingRect: clippingRect
+        )
+        
+// `diagram.cells` now contains doubly linked list of `HalfEdges` and their twins allowing you to continue diagram usage drawing.
+```
+
+# Literature
+
+### Must read:
+1. "Computational Geometry Algorithms and Applications. Third Edition" by Mark de Berg, Otfried Cheong Marc van Kreveld, Mark Overmars (Voronoi diagrams section)
+2. "Introduction to Algorithms. Third Edition" by Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, Clifford Stein (RedBlack Trees section)
+3. [A Sweepline Algorithm for Voronoi Diagrams](http://www.wias-berlin.de/people/si/course/files/Fortune87-SweepLine-Voronoi.pdf) - Steven Fortune's paper
+
+### This project would not be possible without following articles:
+
+1. ([Fortunes Algorithm. Part 1](https://jacquesheunis.com/post/fortunes-algorithm/) and [Fortunes Algorithm Part 2](https://jacquesheunis.com/post/fortunes-algorithm-implementation/) by Jacques Heunis (@jacquesh)
+2. [Fortune's algorithm, the details](https://pvigier.github.io/2018/11/18/fortune-algorithm-details.html) by Pierre Vigier (@pvigier)
+