Update documentation and set up docs-pages

[vikrantdeshpande09876]

Add general documentation for package.

Update code-docstring for execute_nlp_pipeline() and other functions in the NLP script.

"""Returns the cleaned version of the annotation label after performing the following steps:

```python
remove_whitespaces()
expand_word_contractions()
replace_special_chars()
convert_number_to_word()
make_lowercase()
get_root_word()
```

Args:
    input_label (str): Input annotation label text.

Returns:
    str: Cleaned version of the annotation label text.
"""

[vikrantdeshpande09876]

Updated general function docs.
Need to update docs pages.