[libc-commits] [libc] [libc] document supported os ranges (PR #118863)

[Nick Desaulniers via libc-commits]

================
@@ -40,6 +40,16 @@ and MacOS have limited support (may be broken).  The Fuchsia platform is
 slowly replacing functions from its bundled libc with functions from this
 project.
 
+LLVM-libc does not guarantee backward compatibility with operating systems that reaches their EOL.
----------------
nickdesaulniers wrote:

```suggestion
LLVM-libc does not guarantee backward compatibility with operating systems that have reached their EOL.
```

https://github.com/llvm/llvm-project/pull/118863