Add Besu + Teku PoS devnet tutorial

[alexandratran]

Describe the issue

Add tutorial on how to use Besu and Teku to launch a local Casper PoS devnet.

What page has the issue?

n/a

Issue type

Missing content

Change suggestion

No response

More context

No response

Besu documentation issue guidelines

• [X] I read and followed this project's documentation guidelines.

[muddlebee]

launch a local Casper PoS devnet

hey @alexandratran 👋 can you point me to relevant resource for this?

[non-fungible-nelson]

@alexandratran we can discuss if this is still needed.