Docs: ssl-backend-error-when-using-openssl (when installing ovirt-engine-sdk)

When installing `ovirt-engine-sdk-python` with pip, pycurl is also installed as a dependency.
The installation of pycurl can with the following error: `ssl-backend-error-when-using...`

We should explain in the docs how to solve this issue. The solution can be taken from ovirt-engine-sdk-python