Provide basic end-user documentation

I have been using InsightFace for face swapping via the Discord bot. It is super-easy to use and the results are amazing! (10/10)

Then I wanted to use InsightFace locally via the command line. Even as a software developer, I couldn't get it to run. Sorry, but the docs are a disaster and seem to be targeted at your own developers only. (0/10) The [website](https://insightface.ai/) says `pip install -U insightface`, which I did, but that was not sufficient.

The ["documentation"](https://github.com/deepinsight/insightface/tree/master/python-package) does not even mention `pip install -U insightface` As the title and code examples suggest, this is aimed at Python developers who want to integrate InsightFace into their applications. Also, no explanation what the meaning of all these models is. Just in case, I ran `pip install onnxruntime-gpu`.

The [wiki installation instructions](https://github.com/deepinsight/insightface/wiki/INSTALL) are completely cryptic.

Before filing this issue, I found some hidden docs in the form of pinned issue #891. So I have downloaded antelope model files and saved them where I thought may be the model folder `~/.insightface/models/`. I have saved them to both `C:\Users\MyUsername\.insightface\models\antelope\*.onnx` and installation directory `C:\Program Files\Python310\Lib\site-packages\insightface\models\antelope\*.onnx`. But `insightface-cli.exe --help` still gave me the error `ModuleNotFoundError: No module named 'mxnet'`.

After a web search, I did `pip install mxnet`. Now `insightface-cli.exe --help` gives me the error `ImportError: cannot import name 'Mapping' from 'collections' (C:\Program Files\Python310\lib\collections\__init__.py)`

This is too frustrating to waste more time on it.

On a related note, your discoverability of the project is very bad. I had spent hours searching for a software like yours, trying out many commercially available services and also spending many hours on https://github.com/deepfakes/faceswap, getting barely mediocre results. I only have access to your software now because a friend pointed me to a tutorial video that demonstrates how to use your Discord bot.