define skins

README.md

@@ -49,7 +49,7 @@ classes provided in the base skin, as well as entirely replacing components as
 required.
 
 The SDK uses the 'atomic' design pattern as seen at http://patternlab.io to
-encourage a very modular and reusable architecture, making it as easy to
+encourage a very modular and reusable architecture, making it easy to
 customise and use UI widgets independently of the rest of the SDK and your app.
 In practice this means:
 
@@ -70,6 +70,13 @@ In practice this means:
      style organisms into a well-defined global look and feel
    * pages: specific instances of templates.
 
+ * "Skins" refer to a suite of components (views and css) which define the look
+   and feel of the Matrix UI used in the target app.  We provide a 'base' skin
+   in skins/base which provides generic plain UI for typical chat functions.
+   To change the look and feel to embed the SDK into your own app, users can
+   define a new skin which inherits from the base one, or override components
+   in the app itself.  TODO: spell out how.
+
  Good separation between the components is maintained by adopting various best
  practices that anyone working with the SDK needs to be be aware of and uphold: