book: update refs to release-0-7 specific book (#1572)

Signed-off-by: Prajyot-Parab <prajyot.parab2@ibm.com>

docs/book/src/introduction.md

@@ -20,8 +20,9 @@ previous cluster managers such as [kops](https://github.com/kubernetes/kops) and
 
 <h1>Cluster API Provider IBM Cloud documentation versions</h1>
 
-This book documents Cluster API Provider IBM Cloud v0.6. For other versions please see the corresponding documentation:
+This book documents Cluster API Provider IBM Cloud v0.7. For other versions please see the corresponding documentation:
 * [main.cluster-api-ibmcloud.sigs.k8s.io](https://main.cluster-api-ibmcloud.sigs.k8s.io)
+* [release-0-7.cluster-api-ibmcloud.sigs.k8s.io](https://release-0-7.cluster-api-ibmcloud.sigs.k8s.io/)
 * [release-0-6.cluster-api-ibmcloud.sigs.k8s.io](https://release-0-6.cluster-api-ibmcloud.sigs.k8s.io/)
 * [release-0-5.cluster-api-ibmcloud.sigs.k8s.io](https://release-0-5.cluster-api-ibmcloud.sigs.k8s.io/)
 * [release-0-4.cluster-api-ibmcloud.sigs.k8s.io](https://release-0-4.cluster-api-ibmcloud.sigs.k8s.io/)