README.md: Use GFM syntax highlighting for code blocks
README.md: Edit headings
README.md: Edit Introduction
README.md: Edit lists for consistent spacing & bullets
README.md: Minor formatting tweaks (esp. code)
README.md: Edit for spelling, phrasing, and readability
Merge pull request #6 from Zearin/docs/README

README.md: Edit for formatting, phrasing, and readability