update lifecycle hooks documentation with new upgrade rules

Author: Yuvaraj Kakaraparthi

docs/book/src/tasks/experimental-features/runtime-sdk/implement-lifecycle-hooks.md

@@ -115,6 +115,12 @@ This hook is called after the Cluster object has been updated with a new `spec.t
 immediately before the new version is going to be propagated to the control plane (*). Runtime Extension implementers 
 can use this hook to execute pre-upgrade add-on tasks and block upgrades of the ControlPlane and Workers.
 
+Note: While the upgrade is blocked changes made to the Cluster Topology will be delayed propagating to the underlying
+objects while the object is waiting for upgrade. Example: modifying ControlPlane/MachineDeployments (think scale up),
+or creating new MachineDeployments will be delayed until the target ControlPlane/MachineDeployment is ready to pick up the upgrade. 
+This ensures that the ControlPlane and MachineDeployments do not perform a rollout prematurely while waiting to be rolled out again for the version upgrade (no double rollouts).
+This also ensures that any version specific changes are only pushed to the underlying objects also at the correct version.
+
 #### Example Request:
 
 ```yaml
@@ -158,6 +164,12 @@ and immediately before the new version is going to be propagated to the MachineD
 Runtime Extension implementers can use this hook to execute post-upgrade add-on tasks and block upgrades to workers
 until everything is ready.
 
+Note: While the MachineDeployments upgrade is blocked changes made to existing MachineDeployments and creating new MachineDeployments
+will be delayed while the object is waiting for upgrade. Example: modifying MachineDeployments (think scale up),
+or creating new MachineDeployments will be delayed until the target MachineDeployment is ready to pick up the upgrade.
+This ensures that the MachineDeployments do not perform a rollout prematurely while waiting to be rolled out again for the version upgrade (no double rollouts).
+This also ensures that any version specific changes are only pushed to the underlying objects also at the correct version.
+
 #### Example Request:
 
 ```yaml