Add more information about what a TRP server/client is

[EehMauro]

When starting to follow the quickstart there are not references about what a TRP server/client is
But you need to setup one in order to use cshell and run the generated code

Also there are some settings for the trix.toml file that needs to be addressed on the docs:

[profiles.devnet.network]
rpc_url = "http://localhost:8545/"
chain_id = 1337

[profiles.devnet.trp]
url = "https://cardano-preview.trp-m1.demeter.run/"

[profiles.devnet.trp.headers]
dmtr-api-key = "trpjodqbmjblunzpbikpcrl"