Grunt config for infusion-docs

[Bates, Simon]

This morning I created a Grunt config for infusion-docs to build the docs locally:

https://github.com/simonbates/infusion-docs/tree/FLUID-5365

It uses grunt-markdown which in turn uses marked.

The config processes all *.md files in the top level and writes HTML files to an html/ directory.

There will be an issue with local links -- we are currently targeting reading on GitHub and as such our link destinations are the *.md files. With this build config, those links won't work. Let's continue with using the *.md links for now while we figure out our deployment strategy.

Simon