Fix formatting in documentation

Removed trailing whitespaces and extra newlines. Added some missing
punctuation. Replaced unicode characters that aren't commonly used
with the more common character.

The replaced unicode characters are
- ’ (U+2019) to ' (U+0027)
- “ (U+201C) to " (U+0022)
- ” (U+201D) to " (U+0022)

docs/quick-start.md

@@ -101,7 +101,7 @@ If you need any help or support in getting Dashy running, head over to the [Disc
 
 If you're enjoying Dashy, and have a few minutes to spare, please do take a moment to look at the [Contributing Page](https://github.com/Lissy93/dashy/blob/master/docs/contributing.md). Huge thanks to [everyone](https://github.com/Lissy93/dashy/blob/master/docs/credits.md) who has already helped out!
 
-Enjoy your dashboard :) 
+Enjoy your dashboard :)
 
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