[3.12] gh-101100: Define _tkinter module to fix references (GH-112382) (#112392)

gh-101100: Define `_tkinter` module to fix references (GH-112382)

Define _tkinter module to fix references
(cherry picked from commit 6b961b8)

Co-authored-by: Hugo van Kemenade <[email protected]>

Author: miss-islington

Doc/library/tkinter.rst

@@ -232,6 +232,9 @@ The modules that provide Tk support include:
 
 Additional modules:
 
+.. module:: _tkinter
+   :synopsis: A binary module that contains the low-level interface to Tcl/Tk.
+
 :mod:`_tkinter`
    A binary module that contains the low-level interface to Tcl/Tk.
    It is automatically imported by the main :mod:`tkinter` module,