Convert DANGER alerts to WARNING

In &5020 (closed), we decided to use only two alerts (note, warning), and eliminate any bold text coming after the icon.

This issue is about:

1. Getting rid of bold text **Danger:**

   for i in `grep -r "DANGER: \*\*Danger:\*\*" doc | uniq | cut -d':' -f1`; do sed -i 's|DANGER: \*\*Danger:\*\*|DANGER:|' $i; done

2. Converting DANGER alerts into WARNINGs

   for i in `grep -r "DANGER:" doc | uniq | cut -d':' -f1`; do sed -i 's/DANGER:/WARNING:/' $i; done

The above steps will need to be repeated for all 4 products:

• GitLab !49412 (merged)
• Omnibus omnibus-gitlab!4822 (merged)
• Runner gitlab-runner!2610 (merged)
• Charts gitlab-org/charts/gitlab!1699 (merged)