The documentation should be structured better #19

The top-level README file (which is also shown on the package page) needs to be more helpful. Specifically:

• Installation instructions need to be more prominent, and need to link to the Atom documentation for "how to install packages". Optional dependency packages need to be listed with links to the appropriate packages' pages.
• Add links to the package pages and/or documentation for Atom features that the package integrates with, including indentation, auto-completion, snippets, and linting.
• Provide very basic instructions for downloading/extracting LiveCode Server for LCS linting support.