bpo-36182: Update pathlib.Path.write_text() docs (GH-12161) (GH-15977)

with the case of an existing file
(cherry picked from commit af636f4f91b8289b6dad95cb84123f6e22fd7f4f)

Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
diff --git a/Doc/library/pathlib.rst b/Doc/library/pathlib.rst
index ad8f601..326bb2e 100644
--- a/Doc/library/pathlib.rst
+++ b/Doc/library/pathlib.rst
@@ -1106,6 +1106,9 @@
       >>> p.read_text()
       'Text file contents'
 
+   An existing file of the same name is overwritten. The optional parameters
+   have the same meaning as in :func:`open`.
+
    .. versionadded:: 3.5
 
 Correspondence to tools in the :mod:`os` module