Examples submodule

[tuler]

Add submodule to examples 0.16.0

[miltonjonat]

Shouldn't we add something to the README too?

[tuler]

Examples was always separate. The README is more about the code split (node and contracts).

[miltonjonat]

I know, but if there's an examples submodule there could be some mention in the README as to why. Something like the following (in bold):

Continued development will take place at the following repositories:

• Cartesi Rollup node: cartesi/rollups-node
• Cartesi Rollups smart contracts: cartesi/rollups-contracts

Examples are available in cartesi/rollups-examples

For more information about Cartesi Rollups, check the official documentation.