Wiki page with instructions to build the system (kernel) and artifacts

Issue Background

In order to stop using the builds and artefacts provided by Linaro and start using our own, a new wiki page with instructions will be required.

Issue description

• Create a new wiki page with the instructions to build initramfs as starting point to further instructions for building the kernel and other artefacts or systems to be tested.
• Add this wiki page to the content critical path as step 4:
  1. Deployment
  2. Set up and config
  3. Connection to the board
  4. Build system and artefacts
  5. Test
• Change the titles of the content critical path pages to reflect there are five steps now.
• Add link to this new page in the following wiki pages:
  • Testing landing page
  • Download page
  • B@D feature page

Acceptance criteria

• Link to the new wiki page: https://wiki.linuxfoundation.org/civilinfrastructureplatform/cipsystembuildhowto
• Confirmation of the links:
  • From step 3 to 4
  • from step 4 to 5
  • Landing page, download page and feature page.