Auto merge of #1215 - RalfJung:readme, r=RalfJung

readme: mention the leaks we found

Author: bors

README.md

@@ -240,6 +240,7 @@ Definite bugs found:
 * [`rand` performing unaligned reads](https://github.com/rust-random/rand/issues/779)
 * [The Unix allocator calling `posix_memalign` in an invalid way](https://github.com/rust-lang/rust/issues/62251)
 * [`getrandom` calling the `getrandom` syscall in an invalid way](https://github.com/rust-random/getrandom/pull/73)
+* [`Vec`](https://github.com/rust-lang/rust/issues/69770) and [`BTreeMap`](https://github.com/rust-lang/rust/issues/69769) leaking memory under some (panicky) conditions
 
 Violations of [Stacked Borrows] found that are likely bugs (but Stacked Borrows is currently just an experiment):