Move designs.a.o to www.a.o

This series copies across the documents on designs.a.o.

Once this is merged, the majority of the content (apart from the private stuff) can be dropped from designs.a.o.

Documents have been skim checked to see that they appear to be properly rendered. Hugo shortcode refs have been used where possible to increase URL checking when website is generated.

content/architecture/boot_process.md

@@ -37,7 +37,7 @@ read-only for the majority of the system's uptime, there should be few
 opportunities for defects to adversely affect the boot process. More
 serious issues resulting from updates will result in the system returning
 to the pre-update configuration. For more details, please refer to the
-[System Updates and Rollback Proposal](https://designs.apertis.org/latest/system-updates-and-rollback.html).
+[System Updates and Rollback Proposal]( {{< ref "system-updates-and-rollback.md" >}} ).
 
 # Systemd and its role in startup