Docs: Use SVG logo in header

[leoheitmannruiz]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew typecheck with your changes locally?
• Have you successfully run brew tests with your changes locally?

---

As in Homebrew/brew.sh#931

[MikeMcQuaid]

Thanks again @leoheitmannruiz!

[dduugg]

Tests should pass on rebase, my apologies 💔

[leoheitmannruiz]

Ups, not a rebase, sorry.
Does this work though? Hehe