Update documentation header
Update documentation header

Details:
- Update index.rst to be the same header like
  in README.rst

Signed-off-by: Juergen Leopold <2ef4e6fc356c4a0c570adb4e83b64b658f380892@de.ibm.com>

zhmcclient/python-zhmcclient,zhmcclient/python-zhmcclient