Issue 25224: Augment Idle doc feature list and no-subprocess section

to finish making current README.txt obsolete.

Doc/library/idle.rst

@@ -8,7 +8,7 @@ IDLE
    single: Python Editor
    single: Integrated Development Environment
 
-.. moduleauthor:: Guido van Rossum <guido@Python.org>
+.. moduleauthor:: Guido van Rossum <guido@python.org>
 
 IDLE is the Python IDE built with the :mod:`tkinter` GUI toolkit.
 
@@ -18,13 +18,19 @@ IDLE has the following features:
 
 * cross-platform: works on Windows, Unix, and Mac OS X
 
+* Python shell window (interactive interpreter) with colorizing
+  of code input, output, and error messages
+
 * multi-window text editor with multiple undo, Python colorizing,
-  smart indent, call tips, and many other features
+  smart indent, call tips, auto completion, and other features
 
-* Python shell window (a.k.a. interactive interpreter)
+* search within any window, replace within editor windows, and search
+  through multiple files (grep)
 
-* debugger (not complete, but you can set breakpoints, view and step)
+* debugger with persistent breakpoints, stepping, and viewing
+  of global and local namespaces
 
+* configuration, browsers, and other dialogs
 
 Menus
 -----
@@ -530,6 +536,17 @@ If there are arguments:
 Running without a subprocess
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+By default, Idle executes user code in a separate subprocess via a socket,
+which uses the internal loopback interface.  This connection is not
+externally visible and no data is sent to or received from the Internet.
+If firewall software complains anyway, you can ignore it.
+
+If the attempt to make the socket connection fails, Idle will notify you.
+Such failures are sometimes transient, but if persistent, the problem
+may be either a firewall blocking the connecton or misconfiguration of
+a particular system.  Until the problem is fixed, one can run Idle with
+the -n command line switch.
+
 If IDLE is started with the -n command line switch it will run in a
 single process and will not create the subprocess which runs the RPC
 Python execution server.  This can be useful if Python cannot create

Lib/idlelib/help.html

@@ -80,10 +80,15 @@
 <ul class="simple">
 <li>coded in 100% pure Python, using the <a class="reference internal" href="tkinter.html#module-tkinter" title="tkinter: Interface to Tcl/Tk for graphical user interfaces"><tt class="xref py py-mod docutils literal"><span class="pre">tkinter</span></tt></a> GUI toolkit</li>
 <li>cross-platform: works on Windows, Unix, and Mac OS X</li>
+<li>Python shell window (interactive interpreter) with colorizing
+of code input, output, and error messages</li>
 <li>multi-window text editor with multiple undo, Python colorizing,
-smart indent, call tips, and many other features</li>
-<li>Python shell window (a.k.a. interactive interpreter)</li>
-<li>debugger (not complete, but you can set breakpoints, view and step)</li>
+smart indent, call tips, auto completion, and other features</li>
+<li>search within any window, replace within editor windows, and search
+through multiple files (grep)</li>
+<li>debugger with persistent breakpoints, stepping, and viewing
+of global and local namespaces</li>
+<li>configuration, browsers, and other dialogs</li>
 </ul>
 <div class="section" id="menus">
 <h2>25.5.1. Menus<a class="headerlink" href="#menus" title="Permalink to this headline">¶</a></h2>
@@ -503,6 +508,15 @@ set in the Options dialog.</li>
 </div>
 <div class="section" id="running-without-a-subprocess">
 <h3>25.5.4.2. Running without a subprocess<a class="headerlink" href="#running-without-a-subprocess" title="Permalink to this headline">¶</a></h3>
+<p>By default, Idle executes user code in a separate subprocess via a socket,
+which uses the internal loopback interface.  This connection is not
+externally visible and no data is sent to or received from the Internet.
+If firewall software complains anyway, you can ignore it.</p>
+<p>If the attempt to make the socket connection fails, Idle will notify you.
+Such failures are sometimes transient, but if persistent, the problem
+may be either a firewall blocking the connecton or misconfiguration of
+a particular system.  Until the problem is fixed, one can run Idle with
+the -n command line switch.</p>
 <p>If IDLE is started with the -n command line switch it will run in a
 single process and will not create the subprocess which runs the RPC
 Python execution server.  This can be useful if Python cannot create