[DOCS] Code Refactoring and content update of quickstart_workflow.ipynb

[peppinob-ol]

Description

I found the quickstart workflow not as quick as it could be:

• Cells cannot be run straightaway in google colab and need extra work (eg. libraries not imported).
• Some important concepts (eg. records and datasets) are not clearly stated in text and code snippets
• Text refers to the same steps more than once (no clear chain of thought)
• Cells override the same variable (eg. record), so the feeling is more of a cheatsheet than of a tutorial notebook
• Content is not updated (eg. ArgillaTrainer is not ever mentioned in the Train section)

I worked on a new version of the notebook with enhanced code and text cells.Ii added also code snippets for training examples which were only described textually.

One last suggestion: It's advisable that external files (data) are downloaded programmatically by running a cell (eg. using requests library). Snapchat_app_store_reviews.csv and kaffee_reviews.csv are taken from kaggle which requires sign-in, so it's not possible to download them directly. Possible solutions:

• place a copy of the Kaggle datasets in Arggilla's GitHub repository (if permitted by Kaggle's terms of use)
• select other datasets from another source.

Closes #3431

Type of change

(Please delete options that are not relevant. Remember to title the PR according to the type of change)

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor (change restructuring the codebase without changing functionality)
• Improvement (change adding some improvement to an existing functionality)
• Documentation update

How Has This Been Tested

(Please describe the tests that you ran to verify your changes. And ideally, reference tests)

• Test A: code run with latest google-colab (v.1.0.0)

Checklist

• I added relevant documentation
• follows the style guidelines of this project
• I did a self-review of my code
• I made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I filled out the contributor form (see text above)
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)

[davidberenstein1957]

@peppinob-ol thanks a lot for the great PR!