Rancher version requirement (#80)

Rancher version requirement

added requirement for Rancher version

Reviewed-by: Artem Lifshits

.goreleaser.yml

@@ -1,5 +1,6 @@
 # Visit https://goreleaser.com for documentation on how to customize this
 # behavior.
+version: 2
 project_name: docker-machine-driver-otc
 before:
   hooks:
@@ -67,4 +68,4 @@ release:
     owner: opentelekomcloud
     name: docker-machine-opentelekomcloud
 changelog:
-  skip: true
+  disable: true

docs/usage-with-rancher.md

@@ -2,6 +2,9 @@
 
 > !Important note: The current available `docker-machine-opentelekomcloud` is not a part of the Rancher. You need to update the Driver to the latest version to get this properly running. We have an open issue to get this fixed @Rancher, but the approval is currently missing.
 
+### Requirements
+- [Rancher]([https://www.terraform.io/downloads.html](https://ranchermanager.docs.rancher.com/getting-started/installation-and-upgrade)) v2.7.x+
+
 ### Remove old node driver:
 
  * Open Rancher UI page and go to `Tools` → `Drivers` → `Node Drivers`.