feat: add docs for proxy-pass

[jarqvi]

Checklist

• I have read the documentation.
• I have included a pull request description of my changes.
• I have included some tests.
• If it's a new feature, I have included documentation updates in both the README and the types.

[jarqvi]

Hello!
I recently found myself in need of a specific code but couldn't locate a comprehensive solution. Following an examination of the documentation and conducting several tests, I reached the following conclusion.

As a result, I decided it would be beneficial to submit a pull request (PR) for this, along with an illustrative example, to assist others in utilizing it.

[sindresorhus]

I appreciate the pull request, but I feel like documenting Express usage is a bit outside of what we should document in Got. I suggest writing a blog post about it on your blog instead 👍

[jarqvi]

Hi @sindresorhus
Thanks.
What do you think if I provide an example in a PR using my HTTP built-in module? Honestly, I don't have a blog, but I really wanted to share this and thought it might be helpful with documentation updates. 🙂

[sindresorhus]

I'm still going to pass. More docs means more for us to maintain too. Non-essential docs are better done in community blogs.

You could for example share it here: https://dev.to

[jarqvi]

ok, thanks.