docs: add transport and tx-prover endpoint references

[BrianSeong99]

Summary

Document the following active service endpoints and status pages used in client configuration:

Service endpoints

• Transport layer: https://transport.miden.io — private note transport endpoint
• Delegated prover: https://tx-prover.testnet.miden.io/ — remote transaction proving endpoint

These are API endpoints (not web pages) that users need for client setup. Currently undocumented.

Status pages

• Testnet: https://status.testnet.miden.io/
• Devnet: https://status.devnet.miden.io/

Suggested locations

• Client setup / configuration guide
• Network infrastructure reference (if exists)