bpo-45346: Keep docs consistent regarding true and false values (GH-28697) (GH-28698)

diff --git a/Doc/library/ast.rst b/Doc/library/ast.rst
index e21151b..d84c841 100644
--- a/Doc/library/ast.rst
+++ b/Doc/library/ast.rst
@@ -1266,7 +1266,7 @@
    the pattern matches the subject.
 
    ``body`` contains a list of nodes to execute if the pattern matches and
-   the result of evaluating the guard expression is truthy.
+   the result of evaluating the guard expression is true.
 
    .. doctest::