Maintenance of `IntroToPandasGuide` class that provides guide for basics of Pandas library

[bogumilchilinski]

The scope of the issue includes maintenance of the following classes:

• [x] #651

• [x] #652

• [x] #653

• [x] #654

[MichauSzewczyk]

Maintenance has been processed.

[bogumilchilinski]

Call code is missing. Please add the following comment:

The code was checked with the following call:

#```python
#call_code
#```

[bartekvv4]

The code was checked with the following call:

from dynpy.utilities.documents.document import IntroToPandasGuide
IntroToPandasGuide(None);