Docs: GUI documentation consistency

[jonnystening]

Lets have a discussion regarding GUI-docs... who its written for and where we should take it going forward.

• Default module naming... Basic/Default? (ie. Primary panel vs Basic button vs Basic table vs Soft tabs)
• Some modules are named using their plural form, some are not (Basic buttons vs Primary panel vs Soft tabs vs Soft accordion)
• Can we rethink the categorisation of module documentation? Should Modal doc really live on a page called Popovers? As a dev Popovers are a very common pattern of their own. Should Panels, Tabs and Accordions all live on the one Containers page? By considering a grouping like Bootstrap (every module lives on its own page), it gives us more room to write more detailed documentation and provide examples.
• We don't currently mention all module modifiers... ie. Modal sizing options
• Icon documentation is very light. I have added a small mention re colouring (#331 & #337), but this could be more thorough. Icon groups should really be consolidated and brought into example iframes (as per #338 & #339)
• 'Getting started' section sub pages are very hard to find (e.g. https://gel.westpacgroup.com.au/GUI/WBC/getting-started/installing/). Great content, but needs to be more prevalent
• FAQ is also hard to find. These long pages with mixed content areas are lost without navigation menu access.