Revise https://etcd.io/docs/v3.5/tutorials/how-to-create-lease/

[celestehorgan]

Pair up for this one!

This issue was created in preparation for the Contributor Summit docs sprint.

File:https://github.com/etcd-io/website/blob/main/content/en/docs/v3.6/tutorials/how-to-create-lease.md

Per #765, do the following:

• Retitle file "Granting and revoking leases"
• Add prerequisites (etcdctl and a currently running etcd cluster are required)
• Define all variables and flags used in the examples in a bulleted list (in this case, --endpoints, put, get, grant, revoke value --lease, keep-alive`)
• Link to https://etcd.io/docs/v3.5/dev-guide/interacting_v3/#grant-leases so that people can learn more about leases if they need to

When done, the document should have the following sub-sections (## H2 headings):

• Pre-requisites
• Grant a lease
• Revoke a lease (new section, code sample is in https://etcd.io/docs/v3.5/dev-guide/interacting_v3/#revoke-leases)