Remove non-endorsement note

We now have the foundation's endorsement for this work.

Author: tautschnig

doc/src/general-rules.md

@@ -6,8 +6,6 @@
 and we kept a copy of the Rust standard library inside the `library/` folder that shall be used as the verification target for all our challenges.
 We will periodically update the `library/` folder to track newer versions of the [official Rust standard library](https://github.com/rust-lang/rust/).
 
-**NOTE:** This work is not officially affiliated, or endorsed by the Rust project or Rust Foundation.
-
 **Challenges:** Each individual verification effort will have a
 tracking issue where contributors can add comments and ask clarification questions.
 You can find the list of [open challenges here](https://github.com/model-checking/verify-rust-std/labels/Challenge).