stub out icons page in docs

docs/_data/nav.yml

@@ -68,10 +68,10 @@
     - title: Typography
     - title: Vertical align
 
-# - title: Extend
+- title: Extend
-#   pages:
+  pages:
-#     - title: Approach
+    # - title: Approach
-#     - title: Icons
+    - title: Icons
 
 - title: About
   pages:

docs/extend/icons.md

@@ -1,6 +1,24 @@
 ---
 layout: docs
-title: Icon fonts
+title: Icons
+group: extend
 ---
 
-TODO
+Bootstrap doesn't include an icon library by default, but we have a handful of recommendations for you to choose from. While most icon sets include multiple file formats, we prefer SVG implementations for their improved accessibility and vector support.
+
+## Preferred
+We've tested and used these icon sets ourselves.
+
+- [Iconic](https://useiconic.com/open/)
+- [Octicons](https://octicons.github.com/)
+- [Entypo](http://www.entypo.com/)
+
+## More options
+While we haven't tried these out, they do look promising and provide multiple formats—including SVG.
+
+- [Google Material icons](https://material.io/icons/)
+- [Ionicons](http://ionicons.com/)
+- [Feather](http://colebemis.com/feather/)
+- [Dripicons](http://demo.amitjakhu.com/dripicons/)
+- [Ikons](http://ikons.piotrkwiatkowski.co.uk/)
+- [Glyph](http://glyph.smarticons.co/)