Add conda development install guidance

[ericdill]

Hi @lwasser - here's a first pass at a 5-minute read for the moment when a learner who is comfortable with conda encounters pip install -e . for the first time.

The goal is to explain why pip shows up in a conda-based workflow, especially when someone is developing local package code and wants to use it inside an existing conda environment.

Like I said in person, I’ve got no ego here. If this is in the wrong voice, missing the mark, or not the right place for this explanation, that’s totally fine. Happy to iterate with you on it. LMK what you think.

I tried to keep it learner-centered rather than tool-comparison-centered.

Also hey @ocefpaf! lmk what you think too.

[ocefpaf]

LGTM, but I'm also a bit biased. This is the workflow that I use the most. The only comment I have is maybe add --no-build-isolation too? I guess one wants to expose all the package in the conda env for the pip editable install in a situation like that.

[willingc]

Thanks @ericdill. This looks very good. I'm leaving it for @lwasser to make the final edits.

Thanks so much, and it was nice to see you at PyCon.

[ericdill]

@ocefpaf thanks for the review! im also biased. this is how i work too :D
@willingc great to see you too! thanks for the review!

(edit too many exclamations. guess im just happy to interact with yall 😁 )