Adding a README for computed property example.
Tweaking the markdown.
Incorporating feedback and adding "The code" section.
Tweaking markdown
Incorporating feedback.
Breaking up one of the lines.
Breaking on 80 chars
More tweaks.
Tweak tweak.
Tweak
Fixed typo.
Final tweaks.
Tweak tweak
Merge pull request #8 from dart-lang/computed-property-readme

Adding a README for computed property example.