Fix documentation for config_drive boot parameter
Fix documentation for config_drive boot parameter

The "config_drive" boot parameter only accepts a Boolean parameter, but
the documentation says otherwise.

Change-Id: I7cbf5aefbd006d8b5425cd8592bacb5d8435b3c9
Closes-Bug: #1314395

CCI-MOC/python-novaclient,takeshineshiro/python-novaclient,mat128/python-novaclient,CCI-MOC/python-novaclient,guptaankita/python-novaclient,Shihta/python-novaclient,mat128/python-novaclient,JioCloud/python-novaclient,JioCloud/python-novaclient,akash1808/python-novaclient,Shihta/python-novaclient,akash1808/python-novaclient,guptaankita/python-novaclient,takeshineshiro/python-novaclient