gh-84459: Make wording more specific for Path.replace (GH-91853)

#84459

Author: slateny

Doc/library/os.rst

@@ -2348,7 +2348,7 @@ features:
 
 .. function:: replace(src, dst, *, src_dir_fd=None, dst_dir_fd=None)
 
-   Rename the file or directory *src* to *dst*.  If *dst* is a directory,
+   Rename the file or directory *src* to *dst*.  If *dst* is a non-empty directory,
    :exc:`OSError` will be raised.  If *dst* exists and is a file, it will
    be replaced silently if the user has permission.  The operation may fail
    if *src* and *dst* are on different filesystems.  If successful,

Doc/library/pathlib.rst

@@ -1042,7 +1042,7 @@ call fails (for example because the path doesn't exist).
 
    Rename this file or directory to the given *target*, and return a new Path
    instance pointing to *target*.  If *target* points to an existing file or
-   directory, it will be unconditionally replaced.
+   empty directory, it will be unconditionally replaced.
 
    The target path may be absolute or relative. Relative paths are interpreted
    relative to the current working directory, *not* the directory of the Path