message: add setup via pypi
diff: - Python 3.6 or higher
  -**Install it from source**
  +**1. Install it via `pip`**
  +
  +```bash
  +# create and activate a virtual environment e.g.
  +pyenv virtualenv xaynet
  +pyenv activate xaynet
  +
  +pip install xaynet-sdk-python
  +```
  +
  +**2. Build it from source**
  ```bash
  # first install rust via https://rustup.rs/
  @@ -17,8 +27,8 @@ git clone https://github.com/xaynetwork/xaynet.git
  cd xaynet/bindings/python
  # create and activate a virtual environment e.g.
  -pyenv virtualenv xayn
  -pyenv activate xayn
  +pyenv virtualenv xaynet
  +pyenv activate xaynet
  # install maturin
  pip install maturin==0.9.0
  