add ref links for environment variables

Author: arshadd-b

docs/book/src/topics/powervs/creating-a-cluster.md

@@ -181,4 +181,20 @@ following the steps below.
   --control-plane-machine-count=3 \
   --worker-machine-count=1 \
   --flavor=powervs-clusterclass | kubectl apply -f -
-  ```
+  ```
+
+**Note:** Refer below for more detailed information on POWERVS variables.
+- [IBMPOWERVS_CLUSTER_CLASS_NAME](/tasks/experimental-features/cluster-class/index.html)
+- [IBMPOWERVS_SSHKEY_NAME](https://cloud.ibm.com/docs/power-iaas?topic=power-iaas-creating-ssh-key)
+- [IBMPOWERVS_VIP](/topics/capibmadm/powervs/network#1-capibmadm-powervs-network-create)
+- [IBMPOWERVS_VIP_EXTERNAL](/topics/capibmadm/powervs/network#1-capibmadm-powervs-network-create)
+- [IBMPOWERVS_VIP_CIDR](/topics/capibmadm/powervs/network#1-capibmadm-powervs-network-create)
+- [IBMPOWERVS_IMAGE_NAME](https://cloud.ibm.com/docs/power-iaas?topic=power-iaas-conn-COS-custom-image)
+- [IBMPOWERVS_SERVICE_INSTANCE_ID](/topics/capibmadm/powervs/image.html)
+- [IBMACCOUNT_ID](https://cloud.ibm.com/docs/account?topic=account-accountfaqs#account-details)
+- [IBMPOWERVS_NETWORK_NAME](/topics/capibmadm/powervs/network#1-capibmadm-powervs-network-create.html)
+- [IBMPOWERVS_REGION](/reference/regions-zones-mapping.html)
+- [IBMPOWERVS_ZONE](/reference/regions-zones-mapping.html)
+- [COS_BUCKET_REGION](https://cloud.ibm.com/docs/cloud-object-storage?topic=cloud-object-storage-endpoints#endpoints-region)
+- [COS_BUCKET_NAME](https://cloud.ibm.com/docs/cloud-object-storage?topic=cloud-object-storage-getting-started-cloud-object-storage#gs-create-buckets)
+- [COS_OBJECT_NAME](https://cloud.ibm.com/docs/cloud-object-storage?topic=cloud-object-storage-getting-started-cloud-object-storage#gs-add-objects)

docs/book/src/topics/vpc/creating-a-cluster.md

@@ -121,4 +121,13 @@ There are two following variables for controlling the volume size for the boot d
     IBMACCOUNT_ID="ibm-accountid" \
     BASE64_API_KEY=$(echo -n $IBMCLOUD_API_KEY | base64) \
     clusterctl generate cluster ibm-vpc-clusterclass --kubernetes-version v1.26.2 --target-namespace default --control-plane-machine-count=1 --worker-machine-count=2 --from=./templates/cluster-template-vpc-clusterclass.yaml | kubectl apply -f -
-  
+ 
+**Note:** Refer below for more detailed information on VPC variables.
+- [IBMVPC_CLUSTER_CLASS_NAME](/tasks/experimental-features/cluster-class/index.html)
+- [IBMVPC_REGION](/reference/regions-zones-mapping.html)
+- [IBMVPC_ZONE](/reference/regions-zones-mapping.html)
+- [IBMVPC_RESOURCEGROUP](https://cloud.ibm.com/docs/account?topic=account-rgs&interface=ui)
+- [IBMVPC_IMAGE_NAME](https://cloud.ibm.com/docs/vpc?topic=vpc-planning-custom-images)
+- [IBMVPC_PROFILE](https://cloud.ibm.com/docs/vpc?topic=vpc-profiles&interface=ui)
+- [IBMVPC_SSHKEY_NAME](https://cloud.ibm.com/docs/vpc?topic=vpc-managing-ssh-keys&interface=ui)
+- [IBMACCOUNT_ID](https://cloud.ibm.com/docs/account?topic=account-accountfaqs#account-details)