Update reference from KL to IBM Cloud Docs

[gudrun-wolfgram]

In the https://softlayer-api-python-client.readthedocs.io/en/latest/api/managers/image/ topic, there's a reference to product information. The Knowledge Layer reference is no longer current. Please update to reference the following IBM Cloud Docs collection for Image Templates:
https://console.bluemix.net/docs/infrastructure/image-templates/image_index.html

Thanks!

[allmightyspiff]

Updated.

[gudrun-wolfgram]

Thanks @allmightyspiff!