Added doc for using OKE workloads (#31)

Author: connelly38

oke_workloads.md

@@ -0,0 +1,78 @@
+# Oracle NoSQL Database Go SDK: authenticating inside Oracle Cloud OKE Workload containers
+
+The Oracle NoSQL go SDK supports running programs inside OKE Workload containers in OCI. To do
+so, you must add the OCI go SDK to your dependencies, add a short bit of code to your app, and set up OCI policies to enable access to NoSQL.
+These steps are detailed below.
+
+You should read the OCI documentation at [Granting Workloads Access to OCI Resources](https://docs.oracle.com/en-us/iaas/Content/ContEng/Tasks/contenggrantingworkloadaccesstoresources.htm#contengmanagingworkloads_topic-grantingworkloadaccesstoresources-golang). Also, this [tutorial](https://docs.oracle.com/en-us/iaas/developer-tutorials/tutorials/helidon-k8s/01oci-helidon-k8s-summary.htm) is helpful in understanding the steps to create and manage OCI OKE Workloads.
+
+## Add OCI go SDK to your dependencies
+
+To add the OC go SDK as a dependency to your project (if not already using it), run the following command in your top-level go module directory:
+
+```
+go get github.com/oracle/oci-go-sdk/v65@latest
+```
+
+## Add code to your app to use OKE Workload identity
+
+The NoSQL go SDK has a slightly enhanced version of `ConfigurationProvider` interface than the OCI go SDK. As such, there is a bit of extra code needed to use the OKE workload configuration provider in a NoSQL in your app.
+
+First, create a new struct and 2 methods that wrap the OCI `ConfigurationProviderWithClaimAccess`:
+
+```
+import ociauth "github.com/oracle/oci-go-sdk/v65/common/auth"
+
+
+type myConfigProvider struct {
+    ociauth.ConfigurationProviderWithClaimAccess
+}
+
+// ExpirationTime in this case always returns a time in the future, effectively setting no expiration.
+func (c *myConfigProvider) ExpirationTime() time.Time {
+    return time.Now().Add(time.Hour)
+}
+
+// SecurityTokenFile is not applicable to the OKE Workload case
+func (c *myConfigProvider) SecurityTokenFile() (string, error) {
+    return "", fmt.Errorf("myConfigurationProvider does not support SecurityTokenFile")
+}
+```
+
+Then, in your code that creates a SignatureProvider to use with NoSQL, Add the following code to use OKE Workload identity:
+```
+    conf, err := ociauth.OkeWorkloadIdentityConfigurationProvider()
+    if err != nil {
+        return nil, fmt.Errorf("cannot create an Oke Provider: %v", err)
+    }
+    myconf := &myConfigProvider{conf}
+    sp, err := iam.NewSignatureProviderWithConfiguration(myconf, compartmentID)
+    if err != nil {
+        return nil, fmt.Errorf("cannot create a Signature Provider: %v", err)
+    }
+```
+
+## Create OCI Identity Policy to allow NoSQL access from your OKE Workload
+
+This part follows the same pattern as described in  
+ [Granting Workloads Access to OCI Resources](https://docs.oracle.com/en-us/iaas/Content/ContEng/Tasks/contenggrantingworkloadaccesstoresources.htm#contengmanagingworkloads_topic-grantingworkloadaccesstoresources-golang). Here's an example policy to use as a guide:
+```
+Allow any-user to manage nosql-family in compartment app_compartment where all {
+ request.principal.type = 'workload',
+ request.principal.namespace = 'default',
+ request.principal.service_account = 'app-testaccount',
+ request.principal.cluster_id = 'ocid1.cluster.oc1.___________________________'i
+}
+```
+
+Once complete, you should be able to build your app as usual, and deploy it to OKE Workload using `docker` and `kubectl` commands as described in the above-referenced [tutorial](https://docs.oracle.com/en-us/iaas/developer-tutorials/tutorials/helidon-k8s/01oci-helidon-k8s-summary.htm).
+
+## Special note
+
+Note: as of this writing, the OCI go SDK has a small incompatibility with OKE Workloads. See [this issue report](https://github.com/oracle/oci-go-sdk/issues/489) for more details. 
+In short, you need to add two environment settings for the auth to work correctly. They can be in the Dockerfile, in `os.Setenv()` calls, or however else you wish to set the ennvironment for your app. Here's an example of the two values to set in a Dockerfile:
+```
+ENV OCI_RESOURCE_PRINCIPAL_VERSION 2.2
+ENV OCI_RESOURCE_PRINCIPAL_REGION us-ashburn-1
+```
+