Remove blank `Imports:` from `DESCRIPTION`

This fixes the bug which makes a blank line keep re-appearing in the
`DESCRIPTION` file when you run `document()`.

I presume this wouldn't happen if we actually put content in this field,
but we can reinstate it once we need it.
Merge pull request #5 from dvukcevic/fix-description-blank-line

Remove blank `Imports:` from `DESCRIPTION`