Fix links on chezmoi.io (#499)

Fix links on chezmoi.io

Author: twpayne

chezmoi.io/content/_index.md

@@ -105,11 +105,11 @@ don't need chezmoi. Otherwise, read on...
 
 ## How do I start with chezmoi?
 
-[Install chezmoi](docs/INSTALL.md) then read the [quick start
-guide](docs/QUICKSTART.md). The [how-to guide](docs/HOWTO.md) covers most common
-tasks, and there's the [frequently asked questions](docs/FAQ.md) for specific
+[Install chezmoi](/docs/install/) then read the [quick start
+guide](/docs/quick-start/). The [how-to guide](/docs/how-to/) covers most common
+tasks, and there's the [frequently asked questions](docs/faq/) for specific
 questions. For a full description of chezmoi, consult the
-[reference](docs/REFERENCE.md). If all else fails, [open an
+[reference](/docs/reference/). If all else fails, [open an
 issue](https://github.com/twpayne/chezmoi/issues/new).
 
 ## License