First pass at removing outdated info from the documentation based on changes in the 3.0.0 release and adding info on new capabilities

Author: tleonhardt

docs/features/argument_processing.md

@@ -61,10 +61,6 @@ def do_speak(self, opts):
         self.poutput(arg)
 ```
 
-!!! note
-
-    `cmd2` sets the `prog` variable in the argument parser based on the name of the method it is decorating. This will override anything you specify in `prog` variable when creating the argument parser.
-
 ## Help Messages
 
 By default, `cmd2` uses the docstring of the command method when a user asks for help on the

docs/features/generating_output.md

@@ -19,6 +19,11 @@ output you generate must be sent to `self.stdout`. You can use the methods descr
 everything will work fine. [cmd2.Cmd][] also includes a number of output related methods which you
 may use to enhance the output your application produces.
 
+Since `cmd2` has a dependency on the [rich](https://github.com/Textualize/rich) library, all of
+`cmd2`'s output methods can natively render `rich`
+[renderable objects](https://rich.readthedocs.io/en/latest/protocol.html), enabling beautiful and
+complex output.
+
 ## Ordinary Output
 
 The `cmd2.Cmd.poutput` method is similar to the Python
@@ -92,6 +97,16 @@ following sections:
 - [cmd2.string_utils][]
 - [cmd2.terminal_utils][]
 
+The [color.py](https://github.com/python-cmd2/cmd2/blob/main/examples/color.py) example demonstrates
+all colors available to your `cmd2` application.
+
+### Custom Themes
+
+`cmd2` uses a `rich` `Theme` object to define styles for various UI elements. You can define your
+own custom theme using `cmd2.rich_utils.set_theme`. See the
+[rich_theme.py](https://github.com/python-cmd2/cmd2/blob/main/examples/rich_theme.py) example for
+more information.
+
 After adding the desired escape sequences to your output, you should use one of these methods to
 present the output to the user:
 
@@ -110,9 +125,9 @@ to control whether these escape codes are passed through to the terminal or not.
 If you would like to generate output which is left, center, or right aligned within a specified
 width or the terminal width, the following functions can help:
 
-- `cmd2.utils.align_left`
-- `cmd2.utils.align_center`
-- `cmd2.utils.align_right`
+- `cmd2.string_utils.align_left`
+- `cmd2.string_utils.align_center`
+- `cmd2.string_utils.align_right`
 
 These functions differ from Python's string justifying functions in that they support characters
 with display widths greater than 1. Additionally, ANSI style sequences are safely ignored and do not

docs/features/table_creation.md

@@ -7,3 +7,6 @@ excellent support for this feature.
 
 Please see rich's documentation on [Tables](https://rich.readthedocs.io/en/latest/tables.html) for
 more information.
+
+The [rich_tables.py](https://github.com/python-cmd2/cmd2/blob/main/examples/rich_tables.py) example
+demonstrates how to use `rich` tables in a `cmd2` application.

docs/migrating/next_steps.md

@@ -41,6 +41,6 @@ If your program generates output by printing directly to `sys.stdout`, you shoul
 to `cmd2.Cmd.poutput`, `cmd2.Cmd.perror`, and `cmd2.Cmd.pfeedback`. These methods work with several
 of the built in [Settings](../features/settings.md) to allow the user to view or suppress feedback
 (i.e. progress or status output). They also properly handle ANSI colored output according to user
-preference. Speaking of colored output, you can use any color library you want, or use the included
-`cmd2.string_utils.stylize` function. These and other related topics are covered in
-[Generating Output](../features/generating_output.md).
+preference. `cmd2`'s dependency on `rich` makes it easy to add color and style to your output. See
+the [Colored Output](../features/generating_output.md#colored-output) section for more details.
+These and other related topics are covered in [Generating Output](../features/generating_output.md).