Rework workflow documentation

The workflow documentation is a bit of a mess. Rework the documentation:

• Split the details out of the platform guide, making it a better high level overview of Apertis targeted more at selling the platform.
• Create an architectural document covering the basics of the Apertis workflow and how the tools used by Apertis fit together. Use pictures to help explain.
• Detailed information about workflows shifted to guides
  • Packaging guide starting to be restructured to better cover workflows by adding sections.
  • Separating out description of component repository layout into its own guide.
  • Shift image creation details to Image building guide.

While I've noticed:

• Packages have been moved from repository based sub-directories under pkg/ to pkg/ its self. Update the URLs used on the website to reflect this.

Signed-off-by: Martyn Welch martyn.welch@collabora.com

content/architecture/platform-guide.md

@@ -18,7 +18,7 @@ lastmod = "2021-04-29"
 
 Apertis is a versatile open source distribution and associated infrastructure,
 originally tailored to automotive use cases, but which has grown to be a fit
-for a wide variety of electronic devices. Whilst Apertis provides components
+for a wide variety of electronic devices. While Apertis provides components
 both for deployment on target devices and to meet the needs of development
 workflows, these are clearly separated, with special care taken to ensure that
 components intended for deliverables are free from