docs: Update codelab-chat-with-a-pdf.md

[thedmail]

docs: Backports corrections made in google3 (reverts a bunch of angle brackets that got into the file somehow).

Description here... Help the reviewer by:

• linking to an issue that includes more details
• if it's a new feature include samples of how to use the new feature
• (optional if issue link is provided) if you fixed a bug include basic bug details

Checklist (if applicable):

• PR title is following https://www.conventionalcommits.org/en/v1.0.0/
• Tested (manually, unit tested, etc.)
• Docs updated (updated docs or a docs bug required)

[peterfriese]

Hi David - I added these angle brackets to mark the entire block as a note block. I did check this works fine on DevSite before making the change on GitHub.

[thedmail]

Hi David - I added these angle brackets to mark the entire block as a note block. I did check this works fine on DevSite before making the change on GitHub.

Thanks, Peter. It turns out that we were both doing it wrong. :-P I just uploaded a new commit to address the issue.

[peterfriese]

I'd prefer if we could use plain Markdown, but if this is the way we need to things, I'll (begrudgingly) approve.