MacOS installation issues

## Description
The installation instructions for MacOS fails at [step 3.2](https://github.com/AllenCell/aics-segmentation/blob/main/docs/installation_mac.md#step-32-install-the-packages), specifically at `pip install -e .[all]`.
```
Building wheels for collected packages: scikit-image, numba, llvmlite, scikit-fmm
Building wheel for scikit-image (setup.py) ... error
ERROR: Command errored out with exit status 1:
command: /Users/nahyung.choi/opt/anaconda3/envs/segmenter/bin/python -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/fc/6dkngtd52rg1m5mjnwq9krxh0000gp/T/pip-install-3nxi1pk7/scikit-image_9643b29650014f62bf9ee746d7a1304b/setup.py'"'"'; __file__='"'"'/private/var/folders/fc/6dkngtd52rg1m5mjnwq9krxh0000gp/T/pip-install-3nxi1pk7/scikit-image_9643b29650014f62bf9ee746d7a1304b/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' bdist_wheel -d /private/var/folders/fc/6dkngtd52rg1m5mjnwq9krxh0000gp/T/pip-wheel-3jzv7uph
cwd: /private/var/folders/fc/6dkngtd52rg1m5mjnwq9krxh0000gp/T/pip-install-3nxi1pk7/scikit-image_9643b29650014f62bf9ee746d7a1304b/
```

Simply running `pip install aicssegmentation` in a Python 3.7 environment worked, but the PyPI link is buried towards the bottom of the instructions in this note: "Note 4: For advanced user to deploy segmenter on cluster, our package is also available on PyPi"

## Expected Behavior
Either the instructions for installing from source should be updated or the link to the PyPI page should be moved up to the top of the instructions. Probably both.

## Reproduction
Follow the instructions in this repo for MacOS installation.

## Environment
MacOS Big Sur v11.2
conda environment -- tried with Python 3.6, 3.8, and 3.9