Switch Elyra documentation to new style template

[akchinSTC]

Is your feature request related to a problem? Please describe. See the following examples using the new template Gateway Style --> https://jupyter-enterprise-gateway.readthedocs.io/en/latest/ Jupyter Server style --> https://jupyter-server.readthedocs.io/en/latest/?badge=latest

Describe the solution you'd like Create a pilot / sample of our documentation with the new template to test out the changes, and whether we want to proceed

Describe alternatives you've considered

Additional context