Minor quicktour doc suggestions

[stevhliu]

This PR proposes some minor formatting suggestions to the quicktour 🙂

• Some code examples that don't start with >>> don't get copied except for the output.
• Added a link to pipeline and combine so users can click for more details.
• Code format isn't rendered in the right navbar and shows up with the backticks. It might look nicer if we rename the section header or just remove the backticks.

[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.