add more readmes

lib/Readme.md

@@ -0,0 +1,10 @@
+
+This directory contains the core logic of Slate. It's separated into a series of directories, each with their own explanitory Readme:
+
+- [**Components**](./components) — containing the React components Slate renders.
+- [**Models**](./models) — containing the models that store Slate's data.
+- [**Plugins**](./plugins) — containing the plugins that ship with Slate by default.
+- [**Serializers**](./serializers) — containing the serializers that ship with Slate by default.
+- [**Utils**](./utils) — containing a few convenience utility modules.
+
+Feel free to poke around each of them for more information!

lib/serializers/Readme.md

@@ -15,7 +15,7 @@ It handles all of the heavy lifting of actually parsing the HTML, and iterating
 
 #### Raw
 
-The `Raw` serializer is the simplest serializer, which translates a [`State`](../models#state) into JSON. 
+The `Raw` serializer is the simplest serializer, which translates a [`State`](../models#state) into JSON.
 
 It doesn't just use Immutable.js's [`.toJSON()`](https://facebook.github.io/immutable-js/docs/#/List/toJS) method. Instead, it performs a little bit of "minifying" logic to reduce unnecessary information from being in the raw output.
 

lib/utils/Readme.md

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+
+This directory contains a series of utilities that Slate uses internally. They're pulled out here to re-use code and to enforce consistency.