Restructure existing guide to merge with the new one

Update and re-shuffle the existing parts of the apparmor.md guide to merge the old guide with the new guide:

• Update summary with new ref links.
• Reused a few sections but rephrased and updated references.
• Removed a few, no longer needed, sections.

Signed-off-by: Andreas Elvstam Cantner andreas.elvstam@se.bosch.com