Update _posts/2013-01-25-check-comprehension-level.md

Addition of readability testing tool and useful related information.
Update _posts/2013-01-25-check-comprehension-level.md

Removed duplicated word.
Merge pull request #130 from whitingx/gh-pages

Additional readability resource
Update checklist.html

Added one opening `<fieldset>` and a closing one.
Merge pull request #131 from thomassjogren/patch-2

Update checklist.html