Add notebook showing how to rescale photometry values from ERR extension

[bhilbert4]

Add a notebook showing necessary rescaling of photometric uncertainty values when derived from the ERR extension of i2d files in cases where the data have been resampled to a non-native detector pixel scale. This was first reported to the Help Desk in incident INC0202025, and discussed in detail in JP-3680.

Anton has looked over the notebook, and says it looks good.

[sosey]

You're notebook references a requirements.txt file but doesn't include it in this PR. When I create a default env, I still needed to install astroquery after creating a default env with jwst. Check what's in your requirements file and add it to the pr :)

otherwise looked good.

[bhilbert4]

All set. requirements file is in place, and I tested the notebook with the env it creates.

[sosey]

thanks for adding!