Update example and readme.

Author: tdicola

README.rst

@@ -12,7 +12,7 @@ Introduction
     :target: https://discord.gg/nBQh6qu
     :alt: Discord
 
-TODO
+CircuitPython module for control of various small serial thermal printers.
 
 Dependencies
 =============

examples/simpletest.py

@@ -103,6 +103,17 @@
 # Back to normal / small size text.
 printer.set_size_small()
 
+# Print center justified text.
+printer.justify_center()
+printer.print('Center justified!')
+
+# Print right justified text.
+printer.justify_right()
+printer.print('Right justified!')
+
+# Back to left justified / normal text.
+printer.justify_left()
+
 # Print a UPC barcode.
 printer.print('UPCA barcode:')
 printer.print_barcode('123456789012', printer.UPC_A)