add ref links for environment variables (#2172)

Author: arshadd-b

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

@@ -41,6 +41,7 @@ following the steps below.
     > - Set `EXP_CLUSTER_RESOURCE_SET` to `true` as the cluster will be deployed with external cloud provider which will create the resources to run the cloud controller manager.
     > - The `IBMPOWERVS_IMAGE_NAME` value below should reflect the name of the custom image and the `kubernetes-version` value below should reflect the kubernetes version of the custom image.
     > - While working with unreleased versions like from main branch, instead of `--flavor=powervs` use `--from=./templates/cluster-template-powervs.yaml`.
+    > - Refer detailed information on PowerVS variables [here](/topics/powervs/creating-a-cluster#note-refer-below-for-more-detailed-information-on-powervs-variables)
 
     ```console
     IBMPOWERVS_SSHKEY_NAME="my-pub-key" \
@@ -186,4 +187,17 @@ 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 : Name of the cluster that user provides.
+- IBMPOWERVS_SSHKEY_NAME : Name of the SSH Key. Refer [here](/topics/capibmadm/powervs/key#3-capibmadm-powervs-key-list) how to get the keys.
+- IBMPOWERVS_VIP, IBMPOWERVS_VIP_EXTERNAL and IBMPOWERVS_VIP_CIDR : Once we have created the network and port, the values will be available on listing the ports. Refer [here](/topics/capibmadm/powervs/port#3-capibmadm-powervs-port-list)
+- IBMPOWERVS_IMAGE_NAME : Name of the custom image. Refer [here](/topics/capibmadm/powervs/image#2-capibmadm-powervs-image-list) to get image details.
+- IBMPOWERVS_SERVICE_INSTANCE_ID : ID of the PowerVS workspace. Refer [here](https://cloud.ibm.com/docs/power-iaas-cli-plugin?topic=power-iaas-cli-plugin-power-iaas-cli-reference-v1#ibmcloud-pi-workspace)
+- IBMACCOUNT_ID : Go to the Account settings page in the IBM Cloud console to view your account ID and type. The account ID is a 32 character, unique account identifier.Refer [here](https://cloud.ibm.com/account/settings)
+- IBMPOWERVS_NETWORK_NAME : The name of the network. Refer [here](/topics/capibmadm/powervs/network#3-capibmadm-powervs-network-list) how to get the network details.
+- [IBMPOWERVS_REGION](/reference/regions-zones-mapping.html)
+- [IBMPOWERVS_ZONE](/reference/regions-zones-mapping.html)
+- IBM_RESOURCE_GROUP : Go to Manage > Account > Account resources > Resource groups in the IBM Cloud console to get the resource group Name.
+- COS_BUCKET_REGION, COS_BUCKET_NAME and COS_OBJECT_NAME : Refer [here](/machine-images/powervs#powervs-images-with-dhcp-based-network) to get the COS details.

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

@@ -122,4 +122,13 @@ 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 : Name of the cluster that user provides.
+- [IBMVPC_REGION](/reference/regions-zones-mapping.html)
+- [IBMVPC_ZONE](/reference/regions-zones-mapping.html)
+- IBMVPC_RESOURCEGROUP : Go to Manage > Account > Account resources > Resource groups in the IBM Cloud console to get the resource group ID.
+- IBMVPC_IMAGE_NAME : Name of the custom image. Refer [here](/topics/capibmadm/vpc/image#1-capibmadm-vpc-image-list)
+- [IBMVPC_PROFILE](https://cloud.ibm.com/docs/vpc?topic=vpc-profiles&interface=cli)
+- IBMVPC_SSHKEY_NAME : Name of the SSH Key. Refer [here](/topics/capibmadm/vpc/key#1-capibmadm-vpc-key-list) how to get the keys.
+- IBMACCOUNT_ID : Go to the Manage > Account > Account settings page in the IBM Cloud console to view your account ID and type. The account ID is a 32 character, unique account identifier. Refer [here](https://cloud.ibm.com/account/settings)