Update Doc/c-api/frame.rst

Co-authored-by: Mikhail Efimov <efimov.mikhail@gmail.com>

Author: vstinner

Doc/c-api/frame.rst

@@ -227,7 +227,7 @@ Unless using :pep:`523`, you will not need this.
 
    The interpreter's internal frame representation.
 
-   The structure is intentionally opaque and there are currently no plans to
+   The structure is intentionally opaque, and there are currently no plans to
    stabilize it. Debuggers and profilers can use the internal C API to access
    the structure members.