Fix typo in "local devnet" instructions

[JenabaBa]

📝 Summary

Fixed changes for instructions on running a local devnet

current instructions appear as:

when initializing contender
cargo run -- setup ./scenarios/simple.toml http://localhost:2222

and when running contender
cargo run -- spam ./scenarios/simple.toml http://localhost:2222 --tpb 10 --duration 10

but if those lines are ran, it'll produce an error because a '-r' or '-rpc' is needed before the RPC URL

💡 Motivation and Context

This change is required because the current instructions for initializing/running contender throws an error and this fix would make the instructions on running a local devnet a lot clearer

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✅ I have completed the following steps:

• [ x ] Run make lint
• [ x ] Run make test
• Added tests (if applicable)

[SozinM]

Thanks!