Remove the release.rst file
Remove the release.rst file

It has not been updated in a long time and does not seem to be used
Closes-Bug: #1257295

Change-Id: Ie798cc5e6c64db6afcaf22102c74e8be12d3c6a2

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