mention FFI wrapper crates

Author: pietroalbini

posts/2020-11-19-Rust-1.48.md

@@ -149,6 +149,11 @@ With this annotation, if we search for "bar" in rustdoc's search, `Foo` will
 come up as part of the results, even though our search text doesn't have
 "Foo" in it.
 
+An interesting use case for aliases is FFI wrapper crates, where each Rust
+function could be aliased to the C function it wraps. Existing users of the
+underlying C library would then be able to easily search the right Rust
+functions!
+
 [75740]: https://github.com/rust-lang/rust/pull/75740/
 
 ### Library changes