Rollup merge of #37475 - AndiDog:feature/error-explanation-E0532, r=GuillaumeGomez

Add E0532 error explanation

This resolves one of the error list in https://github.com/rust-lang/rust/issues/35347 - just because I stumbled over it today.

I assumed the error code should be removed from `register_diagnostics!` because it's now defined above.

Since that is my first code contribution, please check that all is in order. It would be helpful to know how to run the test for the `compile_fail,E0532` part. I did `make check-stage1-cfail NO_REBUILD=1` but that doesn't test the inlined example.

r? @GuillaumeGomez