Update explore_data.py script for text classification guide

[Extremesarova]

• Started using ngram_range argument in function plot_frequency_distribution_of_ngrams instead of hardcoded value
• Replaced method get_feature_names with get_feature_names_out for compatibility with modern version of sklearn
• Improved title and xlabel for the plot_frequency_distribution_of_ngrams
• Increased the size of the plot to avoid text intersection
• Formatted code
• Fixed grammar issued in the comments

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[Extremesarova]

Hi, @willgoldby!

Can you look at this PR? I've noticed that you are the one who reviews the changes in this repository.

Thanks :)