[api-ref] Fix HTTP method on the manage API
[api-ref] Fix HTTP method on the manage API

Should be a POST and not a GET

Change-Id: Id35e80ed9ea8d7bb224805f9c5026d8199ef2b0d
Signed-off-by: Goutham Pacha Ravi <23768c94a9ff9c3948f2b1373d75b7bec9121063@gmail.com>

openstack/manila,openstack/manila