Lab: Ethereum 101 (v2)

@ZakGriffith and @sfaber34 are going to help with the curriculum for the Lab.

First one is pretty clear: a re-do of the live Ethereum 101 lab (which is there just to showcase the features of the platform).

A few notes:
- This first lab should be pretty light, big picture, open to everyone
- Avoid being too dense (concept + concept + question and repeat -> too heavy). We might need to have some interactive cards here and there.
- Let's use ethereum dot org /learn as a reference
- We should iterate a lot (vs. a big PR). We talked about having a `/labs/ethereum-101-v2` URL for this lab (public, but not linked anywhere) as the best way to go thru it.

Regarding the content itself, concepts that I think the lab should contain:
- Decentralization
- World computer
- Wallets / Accounts
- ETHER
- Transaction / Gas / Mempool
- Real applications of Ethereum

Super light tho... big picture. NO need to go into details (There will be more labs later on)-

Feel free to use this issue to discuss, share ideas, etc. Also, feel free to open PRs to start iterating.

Start by reviewing the proposed /labs/ethereum-101-v2 entry point and ethereum.org/learn, then map the requested concepts into a light, interactive learning flow. Done means a public but unlinked Ethereum 101 lab covering decentralization, the world computer, wallets/accounts, ETHER, transactions, gas, the mempool, and real applications without going into detail.

Written by the indexing model from the issue text.