gh-82006: IDLE doc improvements (#94349)

0. Update text start and stop conditions.
1. Title-case sections but not subsections.
2. Edit Shell Window sections: title, execute, restart.

Doc/library/idle.rst

@@ -357,7 +357,7 @@ for more on Help menu choices.
    single: Clear Breakpoint
    single: breakpoints
 
-Context Menus
+Context menus
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 Open a context menu by right-clicking in a window (Control-click on macOS).
@@ -398,7 +398,7 @@ Squeeze
 
 .. _editing-and-navigation:
 
-Editing and navigation
+Editing and Navigation
 ----------------------
 
 Editor windows
@@ -576,17 +576,29 @@ line to the top of the editor.
 The text and background colors for the context pane can be configured under
 the Highlights tab in the Configure IDLE dialog.
 
-Python Shell window
-^^^^^^^^^^^^^^^^^^^
+Shell window
+^^^^^^^^^^^^
 
-With IDLE's Shell, one enters, edits, and recalls complete statements.
-Most consoles and terminals only work with a single physical line at a time.
+In IDLE's Shell, enter, edit, and recall complete statements. (Most
+consoles and terminals only work with a single physical line at a time).
+
+Submit a single-line statement for execution by hitting :kbd:`Return`
+with the cursor anywhere on the line.  If a line is extended with
+Backslash (:kbd:`\\`), the cursor must be on the last physical line.
+Submit a multi-line compound statement by entering a blank line after
+the statement.
 
 When one pastes code into Shell, it is not compiled and possibly executed
-until one hits :kbd:`Return`.  One may edit pasted code first.
-If one pastes more that one statement into Shell, the result will be a
+until one hits :kbd:`Return`, as specified above.
+One may edit pasted code first.
+If one pastes more than one statement into Shell, the result will be a
 :exc:`SyntaxError` when multiple statements are compiled as if they were one.
 
+Lines containing`'RESTART'` mean that the user execution process has been
+re-started.  This occurs when the user execution process has crashed,
+when one requests a restart on the Shell menu, or when one runs code
+in an editor window.
+
 The editing features described in previous subsections work when entering
 code interactively.  IDLE's Shell window also responds to the following keys.
 
@@ -603,7 +615,8 @@ code interactively.  IDLE's Shell window also responds to the following keys.
 
   * :kbd:`Alt-n` retrieves next. On macOS use :kbd:`C-n`.
 
-  * :kbd:`Return` while on any previous command retrieves that command
+  * :kbd:`Return` while the cursor is on any previous command
+    retrieves that command
 
 Text colors
 ^^^^^^^^^^^
@@ -627,7 +640,7 @@ Highlighting tab.  The marking of debugger breakpoint lines in the editor and
 text in popups and dialogs is not user-configurable.
 
 
-Startup and code execution
+Startup and Code Execution
 --------------------------
 
 Upon startup with the ``-s`` option, IDLE will execute the file referenced by
@@ -894,7 +907,7 @@ with the default subprocess if at all possible.
 .. deprecated:: 3.4
 
 
-Help and preferences
+Help and Preferences
 --------------------
 
 .. _help-sources: