Add a warning about the restriction of gnt-node evacuate
Add a warning about the restriction of gnt-node evacuate

Even though gnt-node evacuate should be able to evacuate all instances
at once, this currently is not the case. Add a warning about this deficit
for the time being.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Michele Tartara <05f7077a2c6cbbdc4af4ba42e3ef89a0df846179@google.com>

dimara/ganeti,apyrgio/ganeti,grnet/snf-ganeti,apyrgio/snf-ganeti,onponomarev/ganeti,mbakke/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,ganeti/ganeti,bitemyapp/ganeti,leshchevds/ganeti,andir/ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,ganeti/ganeti,apyrgio/snf-ganeti,leshchevds/ganeti,dimara/ganeti,yiannist/ganeti,onponomarev/ganeti,bitemyapp/ganeti,ganeti/ganeti,mbakke/ganeti,yiannist/ganeti,grnet/snf-ganeti,leshchevds/ganeti,andir/ganeti,apyrgio/ganeti,mbakke/ganeti