docs(backgroundlayers): add to readme

Author: jenndiaz

components/backgroundlayers/README.md

@@ -1,6 +1,20 @@
 # @spectrum-css/backgroundlayers
 
-> The Spectrum CSS background layers component
+> The Spectrum CSS background layers is a set of utility classes used to apply Spectrum 2 app framing. Consult design documentation for further usage and infomation.
+
+To use these classes add the approproate layers and contexts class to the element that the background styling should be applied. Make note of the context when determing the correct class to use.
+
+Editing Context Classes:
+- `spectrum-BackgroundLayers--elevated`
+- `spectrum-BackgroundLayers--layer2`
+- `spectrum-BackgroundLayers--layer1`
+- `spectrum-BackgroundLayers--pasteboard`
+
+Browsing Context Classes:
+- `spectrum-BackgroundLayers--elevated`
+- `spectrum-BackgroundLayers--layer1`
+- `spectrum-BackgroundLayers--base`
+
 
 This package is part of the [Spectrum CSS project](https://github.com/adobe/spectrum-css).