Cleaned up documentation with symbol usage

Full documentation added in both the usage guide and the sprite README
for SVG symbol sprites. Existing documentation and file formatting
cleaned up somewhat.

README.md

@@ -2,7 +2,7 @@
 
 Material design icons are the official [icon set](http://www.google.com/design/spec/style/icons.html#icons-system-icons) from Google that are designed under the [material design guidelines](http://www.google.com/design/spec).
 
-## 2.1 Update
+### 2.1 Update
 
 The 2.1 update adds 96 new icons!
 
@@ -12,16 +12,27 @@ Check out what's new in the [material icons library](https://www.google.com/desi
 
 Read the [developer guide](http://google.github.io/material-design-icons/) on how to use the material design icons in your project.
 
-## Using sprite sheets
+### Using a font collection
 
-In `css-sprite` and `svg-sprite` are pre-generated sprite sheets. Instructions for using them are in the [sprites documentation](https://github.com/google/material-design-icons/tree/master/sprites).
+The `iconfont` folder contains pre-generated font files that can be included in a project. This is especially convenient for the web; however, it is generally better to link to the web font hosted on Google Fonts:
+
+```html
+<link href="https://fonts.googleapis.com/icon?family=Material+Icons"
+      rel="stylesheet">
+```
+
+Read more in the [font portion](http://google.github.io/material-design-icons/#icon-font-for-the-web) of our full developer guide.
+
+### Using symbols and sprites
+
+The `css-sprite` and `svg-sprite` folders contain pre-generated sprite sheets, as well as svg symbols that can be `<use>`d more directly and with fewer constraints. Instructions for using them are in the [sprites documentation](https://github.com/google/material-design-icons/tree/master/sprites).
 
 ## Polymer icons
 
 If you wish to use the icon set with Polymer, we recommend consuming them via the [`<iron-icons>`](https://github.com/polymerelements/iron-icons) element ([`<core-icons>`](https://github.com/Polymer/core-icons) in v0.5).
 
 ## License
 
-We have made these icons available for you to incorporate them into your products under the [Creative Common Attribution 4.0 International License (CC-BY 4.0)](http://creativecommons.org/licenses/by/4.0/). Feel free to remix and re-share these icons and documentation in your
-products.  We'd love attribution in your app's *about* screen, but it's not required. The only thing we ask is that you not re-sell
-the icons themselves.
+We have made these icons available for you to incorporate them into your products under the [Creative Common Attribution 4.0 International License (CC-BY 4.0)](http://creativecommons.org/licenses/by/4.0/). Feel free to remix and re-share these icons and documentation in your products.
+We'd love attribution in your app's *about* screen, but it's not required.
+The only thing we ask is that you not re-sell the icons themselves.

iconfont/README.md

@@ -1,11 +1,9 @@
-The recommended way to use the Material Icons font is hosted by Google Fonts,
-available here:
+The recommended way to use the Material Icons font is by linking to the web font hosted on Google Fonts:
 
-```
+```html
 <link href="https://fonts.googleapis.com/icon?family=Material+Icons"
       rel="stylesheet">
 ```
 
 Read more in our full usage guide:
 http://google.github.io/material-design-icons/#icon-font-for-the-web
-