* Adding Free Python, Datamining, Machine Learning Books (Corrected Categories)

There were a few issues with my original PR (https://github.com/EbookFoundation/free-programming-books/pull/4866/files), so I forked the main respository and added my updates based on @eshellman 's feedback.

Edits include:
- moving "Top 10 Machine Learning Algos..." by Mathews and Aasim --> Machine Learning
- moving "A Select Overview of Deep Learning" by Fan, Ma, and Zhong --> Machine Learning
- adding "Natural Langauge NLP with Python Tutorial" --> Python
- moving "The Ultimate Guide to 12 Dimensionality Reduction Techniques" by Sharma --> Datamining

Note: there was a linter error coming up in the previous PR that I wasn't sure about (https://github.com/EbookFoundation/free-programming-books/pull/4866)....so hopefully this is all set!

* Update free-programming-books.md

Fixed the four errors coming up in TravisCI (adding extra line, and also some alphabetizing). Should be good to go now!

    445:1-455:191  warning  Incorrect number of blank lines between last section and next heading  blank-lines-1-0-2

    445:1-455:191  warning  Alphabetical ordering: swap l.455 and l.454                            alphabetize-lists

    472:1-509:163  warning  Alphabetical ordering: swap l.506 and l.505                            alphabetize-lists

  2315:1-2408:101  warning  Alphabetical ordering: swap l.2362 and l.2361                          alphabetize-lists