Update text/0000-c-unwind-abi.md

Co-authored-by: Ralf Jung <post@ralfj.de>

text/0000-c-unwind-abi.md

@@ -156,7 +156,7 @@ and may be elided as an optimization).
 Rust frames that do contain pending destructors or `catch_unwind` calls are
 called non-POFs.
 
-Note that a non-POF may _become_ a POF, for instance if all `Drop` objects are
+Note that a non-POF may _become_ a POF during execution of the corresponding function, for instance if all `Drop` objects are
 moved out of scope, or if its only `catch_unwind` call is in a code path that
 will not be executed. The next section provides an example.