Fix theming colors

[jrieke]

📚 Context

The theming docs still use our old primary color from a few years ago, this PR fixes that.

🧠 Description of Changes

• Changed the primaryColor in the code example in theming docs.
• Updated the screenshot that shows the primary color.

Revised:

Insert screenshot of your updated UI/code here

Current:

Insert screenshot of existing UI/code here

💥 Impact

Size:

• [x] Small
• [ ] Not small

🌐 References

• [ ] Notion

Contribution License Agreement

By submitting this pull request you agree that all contributions to this project are made under the Apache 2.0 license.

[sfc-gh-dmatthews]

@jrieke I cherry-picked the image update into a larger PR of fixes where I already updated the the text of the default color config (including text color). If you want to give that a review, I can merge it:

1083