Draft: documentation

[Abbe98]

The README has grown very long even through there is much more documentation needed.

• No documentation about template syntax
• No documentation about template functions inherited from Go
• No template function output examples Add output of template function examples in README #65
• ...

The Snowman manual/documentation is supposed to be both a comprehensive guide to using Snowman and a reference for all the features and commands available in Snowman. This is the start of that.

• Basic documentation structure
• Introduction
• Installation
• Quick start
• Reference
  • CLI
  • Template functions
  • Configuration
• Recipes

Tier 2 (very optional for now):

• Guides
• Template functions output examples Add output of template function examples in README #65
• CLI examples
• Snowman internals