Proofreading/editing Getting Started for readability. Attempt 2, this time without extra files.
- [ ] closes #xxxx (Replace xxxx with the GitHub issue number)
- [ ] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

From my original PR:
_I noticed that the Getting Started page had some typos and issues with sentence structure. I went through and modified index.rst to reflect what I hope are some quality changes in readability.
Thanks for checking out my ideas!_

In the original PR I had accidentally committed an extra dozen images of graphs. After some fumbling with GitHub on my part, @mroeschke suggested a new PR would be the easiest way to get going. 
Thanks @shindelr 