docs: upload progress

[trim21]

Summary

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.

[Kludex]

Should we just include a blog post about it instead of including in the docs?

[tomchristie]

Should we just include a blog post about it instead of including in the docs?

Valid question. Seems reasonable to include it in the docs seeing as we've got download tracking examples?

Aside: The other kind of upload tracking would be tracking multipart file uploads. Exercise for the reader.

[trim21]

Seems reasonable to include it in the docs seeing as we've got download tracking examples?

Why I submit this pr

[trim21]

@tomchristie Any more suggestion?

[tomchristie]

Looks pretty good to me.
Walrus, so only works with 3.8+ but that's probs okay.
httpbin takes a long time to return the response from that endpoint which is a bit confusing when running the sample, but again probably fine.

[trim21]

Walrus, so only works with 3.8+ but that's probs okay.

python 3.7 reached its EOL 2 weeks ago...

[trim21]

Looks pretty good to me. Walrus, so only works with 3.8+ but that's probs okay. httpbin takes a long time to return the response from that endpoint which is a bit confusing when running the sample, but again probably fine.

So any progress?

[tomchristie]

We okay with this @encode/maintainers?

(Hit merge if ya think so I guess)

[karpetrosyan]

Great!