Update README.md

[jeanniefinks]

Corrected typos and grammatical issues; this page was linked from NM website, as a CTA.

Specifically noting:

• NM is using the spelling "fine-tuning" and NOT finetuning (or fineuning).
• The word "please" is not used in technical writing.
• Periods should be added to sentences in bulleted lists (like this list).
• Suggestion: run doc through a spell and grammar checker if unsure.