Fix framework link in policy migration merge request

What does this MR do and why?

This MR makes sure we're using absolute url for pointing to compliance framework instead of relative, which is parsed incorrectly inside of markdown

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

How to set up and validate locally

1. Enable feature flag ff_compliance_pipeline_maintenance_mode in rails console (rails c): Feature.enable :ff_compliance_pipeline_maintenance_mode
2. Visit compliance center Docs
3. Create a framework which uses pipeline configuration path
4. Save framework, enter editing of this framework
5. Click 'Migrate pipeline to a policy'
6. Observe prefilled form
7. Create merge request
8. Observer description includes absolute url

Related to #474383 (closed)