update markdown typos in basic retrieval and deep recommender tutorials

[yufengg]

Only updated the .py files initially, but then realized that there were md and ipynb files too. So now it's all bundled in a ball of mess.

[divyashreepathihalli]

/gemini review

[gemini-code-assist]

Code Review

This pull request correctly fixes several typos and formatting issues across the basic_ranking and deep_recommender tutorial files. The changes improve the readability and professionalism of the documentation.

To make the typo cleanup more comprehensive, you might consider addressing two other points, which would be a great addition to this PR:

1. Another typo: The word "simplication" appears in some files where it should be "simplification". I've found it in:

   • examples/keras_rs/basic_ranking.py (lines 65, 79)
   • examples/keras_rs/ipynb/basic_ranking.ipynb (lines 105, 133)
   • examples/keras_rs/md/basic_ranking.md (lines 71, 86)

2. Missed file: The file examples/keras_rs/basic_retrieval.py seems to have been missed. It contains both typos: "need do know" (lines 122, 144) and "simplication" (lines 120, 142). It would be great to update this file and its corresponding ipynb and md versions as well for consistency.

Addressing these would make this valuable cleanup effort more complete. The current changes are a good step forward.