Fix spelling errors in README
Improve punctuation in README
Reword for clarity
Separate all list items with a newline

GitHub wraps <li> contents in a <p> tag when either 1) this newline is
present, or 2) the content contains more than one
paragraph. Otherwise, the content appears directly under the <li>
tag. This results in inconsistent spacing between list items as
rendered on github.com.
Merge pull request #4 from sumbach/readme-improvements

README improvements