Fix the training page readability

Problem

The titles on https://about.gitlab.com/training/ are no longer readable. Also the it's not really clear that we offer 1 workshops. I think if we made the titles more clear and indented the workshop descriptions we could really improve this page.

But at a minimum we should change the color of the headings so they are visible.

Action items

• Darken the titles on the training page so they are visible. Perhaps use the GitLab yellow brand color we use on the homepage in the "move from idea to production" section
• Indent the text under each title so its clear that the text below the title is descriptive
• For the learning Git and GitLab Basics workshop

• Move the GitLab workshop above the Git workshop and change the title of it to "Part 1: GitLab Flow workshop"
• Rename the Git workshop to "Part 2: Git workshop"