Add examples of Cloud Object Storage credentials in README and function inline documentation

[gadamc]

It would be helpful to include examples of the credentials in the documentation. There are often variations in the names of keys and by providing examples, we may help to overcome some confusions.

For example, when I initially when through the COS tutorial, I thought the resource_instance_id was 'cos-bluemix-s3', which was the name of the object storage instance I provisioned. This tripped me up for a while until I was told by somebody else that the resource_instance_id should look like : crn:v1:bluemix:public:cloud-object-storage:global:a/7xxxx:aaaaaa-bbbbb-cccc-dddd-eeeeeeeeee::

So, these examples help.