Invalid escape sequence in doc-strings.

[Paebbels]

Proposed fixes:

• Some doc-strings contain wrong text snippets: True\False → True/False
  See #19
• Fixed reference to pyTooling
  See #20

This causes errors when using itertree:

  C:\Program Files\Python3.11\Lib\ast.py:50: in parse
    return compile(source, filename, mode, flags,
E     File "C:\Program Files\Python3.11\Lib\site-packages\itertree\itree_mathsets.py", line 580
E       """
E       ^^^
E   SyntaxError: invalid escape sequence '\F'

[BR1py]

I have approved the Pull requests, hope all illegal escapes are out now.