Revise https://etcd.io/docs/v3.6/tutorials/how-to-transactional-write.md

[celestehorgan]

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-transactional-write.md

Per #765, do the following:

• Add prerequisites (etcdctl and a currently running etcd cluster are required)
• Define all variables and flags used in the examples in a bulleted list
• Explain txn and why you might want to transactionally write things (might need a maintainer to help with this!)

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

• Pre-requisites
• Performing a transactional write

[jmhbnz]

/retitle Revise https://etcd.io/docs/v3.6/tutorials/how-to-transactional-write.md

[ufenx]

Hi @jmhbnz, seems like this issue is part of the kubecon EU hackathon and I'm not sure if this is still required. If still help wanted, please assign to me so I will work on this.

[wendy-ha18]

/assign
I'm working on this issue

[jberkus]

Because we have Wendy working on this now, I'm going to remove part of this issue:

Explain txn and why you might want to transactionally write things (might need a maintainer to help with this!)

That does NOT belong in this Task. That needs its own, rather extensive doc. I'll open a separate issue.