pySim-shell: Migrate from optparse to argparse for the main()

We're using argparse internally for all shell commands, and can
use that to auto-generate command reference in the manual.

Let's switch to argparse for the main program, too - and generate
the related reference in the manual.

Change-Id: I77c946dbeb9f746fe3d8051173e59462dc2fb5e2
diff --git a/docs/shell.rst b/docs/shell.rst
index 30938fe..4cdf9e0 100644
--- a/docs/shell.rst
+++ b/docs/shell.rst
@@ -23,6 +23,20 @@
 * tab completion of commands and SELECT-able files/directories
 * interactive help for all commands
 
+Running pySim-shell
+-------------------
+
+pySim-shell has a variety of command line arguments to control
+
+* which transport to use (how to use a reader to talk to the SIM card)
+* whether to automatically verify an ADM pin (and in which format)
+* whether to execute a start-up script
+
+.. argparse::
+   :module: pySim-shell
+   :func: option_parser
+
+
 
 cmd2 basics
 -----------