bpo-39852: IDLE 'Go to line' deletes selection, updates status (GH-18801)

It appears standard that moving the text insert cursor away from a selection clears the
selection.  Clearing prevents accidental deletion of a possibly off-screen bit of text.
The update is for Ln and Col on the status bar.
diff --git a/Doc/library/idle.rst b/Doc/library/idle.rst
index fd6e309..b1192e7 100644
--- a/Doc/library/idle.rst
+++ b/Doc/library/idle.rst
@@ -142,7 +142,9 @@
    Open a search-and-replace dialog.
 
 Go to Line
-   Move cursor to the line number requested and make that line visible.
+   Move the cursor to the beginning of the line requested and make that
+   line visible.  A request past the end of the file goes to the end.
+   Clear any selection and update the line and column status.
 
 Show Completions
    Open a scrollable list allowing selection of keywords and attributes. See