README example does not work

[hannob]

Trying to run the example code from the README file I get:

Traceback (most recent call last):
  File "/tmp/dh/./dh", line 26, in <module>
    note.content.add("Test Node 1")
    ^^^^^^^^^^^^^^^^
AttributeError: 'StringElement' object has no attribute 'add'

I believe a similar change to this needs to be applied:
b2d839f

[kuhntob]

You are right, the example was not updated after Note model change #69. To make it work, you can use:

doc.header.notes.add(IncludedNote(content="Test Node 1"))

instead of

note = IncludedNote()
note.content.add("Test Node 1")
doc.header.notes.add(note)

I've created the pull request #89 to update the example on the README