Change `handleDocs` to pattern matching
Let headers have there own line

For lines with `===` h1 and `---` h2 to have a line of it own and not be
grouped with the documentation under it.
Add documentation for `handleHeaders`
Merge branch 'header-newline'
Add documentation explaining `newlines` function
Add explanation for `insert` helper in `newlines`
Merge branch 'more/documentation'
Version bump to 0.5.1