Add Flux to list of approved tools (#455)

This is a fix-up to #403, where Flux was integrated into CI. While at
it, also make that list of tools lexicographically sorted.

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 and MIT licenses.

---------

Co-authored-by: Felipe R. Monteiro <[email protected]>

Author: tautschnig

doc/src/tools.md

@@ -11,10 +11,7 @@ please see the [Tool Application](general-rules.md#tool-applications) section.
 
 | Tool                | CI Status |
 |---------------------|-------|
+ | ESBMC (GOTO-Transcoder) | [![ESBMC](https://github.com/model-checking/verify-rust-std/actions/workflows/goto-transcoder.yml/badge.svg)](https://github.com/model-checking/verify-rust-std/actions/workflows/goto-transcoder.yml)      |
+ | Flux  | [![Flux](https://github.com/model-checking/verify-rust-std/actions/workflows/flux.yml/badge.svg)](https://github.com/model-checking/verify-rust-std/actions/workflows/flux.yml)      |
  | Kani Rust Verifier  | [![Kani](https://github.com/model-checking/verify-rust-std/actions/workflows/kani.yml/badge.svg)](https://github.com/model-checking/verify-rust-std/actions/workflows/kani.yml)      |
- | GOTO-Transcoder (ESBMC) | [![GOTO-Transcoder](https://github.com/model-checking/verify-rust-std/actions/workflows/goto-transcoder.yml/badge.svg)](https://github.com/model-checking/verify-rust-std/actions/workflows/goto-transcoder.yml)      |
  | VeriFast for Rust   | [![VeriFast](https://github.com/model-checking/verify-rust-std/actions/workflows/verifast.yml/badge.svg)](https://github.com/model-checking/verify-rust-std/actions/workflows/verifast.yml)      |
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