Add custom jumbotron params

Created by: flora8984461

This is inspired by https://github.com/EclipseFdn/ecdtools.eclipse.org/issues/96#issuecomment-794110285

An example will be https://deploy-preview-206--eclipsefdn-hugo-solstice-theme.netlify.app/custom-jumbotron/

Signed-off-by: Yi Liu yi.liu@eclipse-foundation.org