Add details to readme

Author: Nycto

README.md

@@ -4,3 +4,29 @@ Dithering algorithms implemented in Nim
 ## API
 
 [API Documentation](https://nycto.github.io/dither-nim/)
+
+## Algorithms
+
+This library supports two primary classifications of algorithms:
+
+* __[Ordered Dithering](https://en.wikipedia.org/wiki/Ordered_dithering)__: This is a fast dithering algorithm that uses
+  a matrix of predefined values to vary what color is selected.
+* __[Error Diffusion](https://en.wikipedia.org/wiki/Error_diffusion)__: A slightly slower dithering algorithm that
+  tracks the error incurred when a color is clamped to the palette, then distributes that error to surrounding pixels.
+
+A more detailed list of supported algorithms can be found here:
+
+https://nycto.github.io/dither-nim/dither/types.html#DitherModes
+
+## Example
+
+A working example that uses [pixie](https://github.com/treeform/pixie) for images and
+[chroma](https://github.com/treeform/chroma) for colors can be seen here:
+
+https://github.com/Nycto/dither-nim/blob/main/example/src/dither_img.nim
+
+## A note on concepts
+
+This library uses Nim [concepts](https://nim-lang.org/docs/manual_experimental.html#concepts) to control the inputs
+to its algorithms. This allows it to integrate with arbitrary image, color, and palette libraries -- as long as they
+implement the interface described by the concepts.