added docinfo header and footer section

- how to create docinfo file
- how to name docinfo file
- set docinfo attributes
- substitute attributes in docinfo file
- related to #88
- related to https://github.com/asciidoctor/asciidoctor/issues/116
- related to https://github.com/asciidoctor/asciidoctor/issues/403
- related to https://github.com/asciidoctor/asciidoctor/issues/486
resolves #88 update quick ref with 0-1-4 changes

- link to icon info in user manual
- inter-doc references
- video macro
- code block with non-select callouts
- code block with xml callout
- pygments
- checklist
- list marker styles
- list number styles
- implicit table header row
- options shorthand
- role and anchor inline shorthand
- image formatting
- toc syntax
- include content form URI
- role for backticked text
- section with link to user manual and help
change prompt to $, fix callout examples
fix callouts and links w/ commas, use listing block delimiters
Merge pull request #104 from graphitefriction/quick-syntax-0-1-4

resolves #88 update quick ref with 0-1-4 changes
Merge pull request #103 from graphitefriction/docinfo-content

added docinfo header and footer section
fix invalid paragraph style
update Id, Role and Options section title