Update theming docs and README a bit.

README.md

 ```
 
 ## Theming
-A default theme, hyde, is provided. Themes are made using Google's closure-template and the source for [hyde](https://github.com/redline6561/coleslaw/tree/master/themes/hyde) should be simple and instructive until I can provide better docs.
+Two themes are provided: hyde and readable (based on [bootswatch readable](http://bootswatch.com/readable/)). Hyde is the default. A guide to creating themes for coleslaw lives [here](https://github.com/redline6561/coleslaw/blob/master/docs/themes.md).

docs/themes.md

 to use. However it does require some knowledge of HTML, CSS, and how
 coleslaw processes content.
 
-To understand how coleslaw processes a blog, a look at the [overview][ovr]
-documentation may prove useful. This document will focus mainly on the
-template engine and how you can influence the resulting HTML.
+To understand how coleslaw processes a blog, a look at the
+[overview][ovr] and [hacking][hck] documentation may prove
+useful. This document will focus mainly on the template engine and how
+you can influence the resulting HTML.
 
 **NOTE**: Themes are not able to change the generated file names or the
 generated file structure on disk. They can change the resulting HTML, nothing more.
 
 As mentioned earlier, most files have a file name which is a slug of
 some sort. So if you want to create a link to a tag file you should
-do something like this: `<a href="${config.domain}/tags/{$tag.slug}">{$tag.name}</a>`.
+do something like this: `<a href="${config.domain}/tags/{$tag.slug}.{$config.pageExt}">{$tag.name}</a>`.
 
 [clt]: https://developers.google.com/closure/templates/
 [ovr]: https://github.com/redline6561/coleslaw/blob/master/docs/overview.md
+[hck]: https://github.com/redline6561/coleslaw/blob/master/docs/hacking.md