docs: add Nvelox to Use cases list

[RedOne-Guerad]

1. Are you opening this pull request for bug-fix, optimization or new feature?

Optimization / Documentation (Adopter Registration)

2. Please describe how these code changes achieve your intention.

I am the creator of Nvelox, an open-source L4 load balancer and proxy. We have chosen gnet as our core networking engine to handle high-concurrency TCP and UDP traffic.

Nvelox leverages gnet's multi-reactor implementation to support:

• Mass Port Binding: Efficiently managing ranges of thousands of ports (e.g., 10k-20k) with a single listener configuration.

• Low Memory Footprint: In our v0.2.1 production-ready tests, we successfully managed 2,056 active ports (1,028 TCP / 1,028 UDP) with a resident memory usage of only 243MB.

• L4 Stickiness: Implementing UDP session tracking on top of gnet's event loops.

We would like to be added to the "Use cases" list to demonstrate how gnet is being used to build high-performance, infrastructure-level networking tools.

3. Please link to the relevant issues (if any).

N/A (Registering as a new adopter/user case).

4. What documentation changes (if any) need to be made/updated because of this PR?

The README.md is updated to include Nvelox in the "Use cases" or "Adopters" table:

Project | Description -- | --   | A high-performance, dual-protocol (TCP/UDP) load balancer and proxy powered by gnet.

4. Checklist

• I have squashed all insignificant commits.

• I have commented my code for explaining package types, values, functions, and non-obvious lines. (N/A - Documentation only)

• I have written unit tests and verified that all tests passes (if needed).

• I have documented feature info on the README (only when this PR is adding a new feature).

• (optional) I am willing to help maintain this change if there are issues with it later.

[panjf2000]

Sorry for the delay. This is a list of corporations/organizations, is there a company using this open-source project?