Is it possible to read the documentation of previous versions? Tried it, looked for answers but no success so far.
There is no hosted documentation for previous versions, no. You can, however, generate the docs yourself and view them locally if you wish. Below are the steps to do so, which I would recommend doing inside a temporary virtual environment.
$ git clone https://github.com/boto/botocore.git
$ cd botocore
$ git checkout $RELEASE_COMMIT
$ pip install -r requirements.txt
$ pip install -r requirements-docs.txt
$ pip install -e .
$ cd docs
$ make html
$ open build/html/index.html
You can easily find the release commits here.