What is the web-template used by many tech documentation web?

everyone.

I found that following websites have the similary style (or, theme or template):

keras: https://keras.io/
conda: https://conda.io/docs/index.html 
thundersvm: https://thundersvm.readthedocs.io/en/latest/ 
chainer: http://docs.chainer.org/en/stable/index.html 

and so on...

Many tech documentation websites use this style (or template). My question is what the template is and how I can use it in my tech blog.

Thank you!