Add documentation for autoscaling in Welkin

[Pavan-Gunda]

Describe the improvement
Add documentation for Autoscaling. The document explains Cluster autoscaling and pod autoscaling in general and then dives into welkin specifics such as,

• How can a reader determine if cluster autoscaling is available in welkin
• How can pod autoscaling be used in welkin
• A running example of user-demo, showing the commands used to trigger an increased load, launching a new pod and a new node.

Screenshots
If applicable, add screenshots to help explain your problem.

Definition of done
There is now documentation for autoscaling in the navbar after CI/CD

[viktor-f]

Could this be merged with this issue: #799 ?
I think they have some overlap.

[Pavan-Gunda]

Could this be merged with this issue: #799 ? I think they have some overlap.

Yes, I'll close this issue in favor of #799 and update the other one.