gh-86017: Improve font actual docs

Doc/library/tkinter.font.rst

@@ -47,7 +47,16 @@ The different font weights and slants are:
 
    .. method:: actual(option=None, displayof=None)
 
-      Return the attributes of the font.
+      Returns information about the actual attributes that are obtained when
+      the font is used on *displayof*; the values obtained may differ from
+      those given (and retrieved by :meth:`Font.cget`) due to
+      platform-dependent limitations (such as the availability of font
+      families and pointsizes). If *displayof* is omitted, it defaults to the
+      main window.
+
+      If *option* is specified, the value of just that attribute is returned;
+      if it is omitted, the return value is a dictionary of all the attributes
+      and their values. See above for a list of the possible attributes. [1]_
 
    .. method:: cget(option)
 
@@ -59,7 +68,7 @@ The different font weights and slants are:
 
    .. method:: copy()
 
-      Return new instance of the current font.
+      Return new instance of the current font with a different *name*.
 
    .. method:: measure(text, displayof=None)
 
@@ -93,4 +102,10 @@ The different font weights and slants are:
 
 .. function:: nametofont(name)
 
-   Return a :class:`Font` representation of a tk named font.
+   Return a :class:`Font` representation of a tk named font.
+
+References
+----------
+
+.. [1] Tk 8.6 font man page
+   https://www.tcl.tk/man/tcl8.6/TkCmd/font.htm#M5