Update Doc/library/pathlib.rst

Co-authored-by: Adam Turner <[email protected]>

Doc/library/pathlib.rst

@@ -1280,7 +1280,7 @@ call fails (for example because the path doesn't exist).
    If *exist_ok* is false (the default), :exc:`FileExistsError` is
    raised if the target directory already exists.
 
-   If *exist_ok* is true, :exc:`FileExistsError` is raised only if the given
+   If *exist_ok* is true, :exc:`FileExistsError` will not be raised unless the given
    path already exists in the file system and is not a directory (same
    behavior as the POSIX ``mkdir -p`` command).