RO-84 - Document CSS classes

[vallerance-bot]

Key: RO-84
Type: Story
Epic: Documentation
Labels: 
Priority: Medium
Affects Versions: 
Status: Backlog
Fix Versions: 

Document the CSS classes available to users for style customizations. Use visual aids to indicate which elements are labeled with which class.

Document how CSS classes relate to the semantic versioning of the library:

• Renaming/removing classes - major version only
• Removing elements labeled with existing class - major version only
• New classes - minor version
• New elements labeled with existing class - minor version, but potentially backwards incompatible!

Document the distinction between {{.orcus-app}} and {{.orcus-window}}: {{.orcus-window}} should be used to style the actual window ui (title bar, scroll bar, etc...), {{.orcus-app}} should be used to style a logical app module. In the future, not all apps may be represented by windows.