Update template guide

Problem

With the new CI/CD Catalog we want GitLab team members to stop contributing CI templates and create components instead, in addition since we are converting existing template to components users needs to be aware that any change they introduce to an existing template needs to be implemented in its components

Proposal

Update the CI templates dev guides and instruct users to

1. Discontinue contributing through CI templates and instead create component projects published in the catalog.
2. In case they patch and update the template they should do it in the relevant component as well since we need to keep them in parity