Fix numbering of footnotes

The footnotes at the bottom of the document are not displayed properly.

Solution:

They should be re-numbered to avoid skips and no longer trigger Pandoc errors.

Notes:

Need to number footnotes ^273 and on; since ^274 was removed, and it wasn't re-numbered in that commit.

I did accomplish this with regex and sed but I checked the links afterward and they're fine:

#!/bin/bash

sed -i 's/\[\^329\]/\[\^328\]/g' guide.md
sed -i 's/\[\^330\]/\[\^329\]/g' guide.md
sed -i 's/\[\^331\]/\[\^330\]/g' guide.md
... snip ...
sed -i 's/\[\^538\]/\[\^537\]/g' guide.md

Fixes #117 (closed)