Add guide to working with conda-build

[travishathaway]

What is the idea?

Conda auth can be used with conda build but it needs to be configured in a certain way. This needs to be documented in our documentation.

What should happen?

Conda build can only be use with conda auth if the channels are specified in the .condarc file. We need to add instructions that tell users to run conda config --add channels <channel_name> (or by just editing this file) for the channel that they need to use before trying to use authenticated channels with conda auth.

[buhrmann]

Good to know! I tried to reopen this one here: #28 (comment), but maybe the problem is simply the missing conda config --add channels... Will give it a try.

[buhrmann]

Can confirm the following works :)

RUN conda config --add channels conda-forge --add channels https://repo.prefix.dev/graphext \
    && conda auth login https://repo.prefix.dev/graphext --token ${PREFIX_RO_TOKEN} \
    && conda build -c https://repo.prefix.dev/graphext -c conda-forge libs/core

But would you know why it may fail with boa/mambabuild when called like this?

RUN conda config --add channels conda-forge --add channels https://repo.prefix.dev/graphext \
    && conda auth login https://repo.prefix.dev/graphext --token ${PREFIX_RO_TOKEN} \
    && micromamba auth login https://repo.prefix.dev --bearer ${PREFIX_RO_TOKEN} \
    && conda mambabuild -c https://repo.prefix.dev/graphext -c conda-forge libs/${PKG}

...
File "/opt/conda/lib/python3.9/site-packages/conda_auth/handlers/token.py", line 105, in __init__
    raise CondaAuthError(
conda_auth.exceptions.CondaAuthError: Unable to find authorization token for requests with channel https://repo.prefix.dev/graphext

I would like to use boa because it still seems to be a bit faster (probably the repo access/parallel downloads), but for it to work I need to (also?) authenticate with micromamba. Could it be that the two are stepping on each other's feet somehow?