Update Notepad tutorial documentation to match code

Some recent CLs to the Notepad source files fixed a couple of bugs in the
code:

http://b/issue?id=2266994
http://b/issue?id=2266962

This CL includes the newly corrected code in the zip file that developers
download.  The zip file was generated as follows:

cd development/tutorials
zip -r /tmp/NotepadCodeLab NotepadCodeLab -x \*Android.mk

This CL also updates the documentation to match the new version of the
code.  Thus the code the users generate will include the bug fix.