Improve description of compare_attributes arg

Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>

Author: jeremyhylton

Doc/library/ast.rst

@@ -2479,7 +2479,7 @@ effects on the compilation of a program:
    *compare_attributes* affects whether AST attributes are considered
    in the comparison. If compare_attributes is ``False`` (default), then
    attributes are ignored. Otherwise they must all be equal. This
-   option is useful to look for asts that are structurally equal but
+   option is useful to check whether the ASTs are structurally equal but
    might differ in whitespace or similar details.
 
    .. versionadded:: 3.14