I had forgotten how I did this and couldn't find notes, so... here's
how:
```
grep -Eo '`#([0-9]+)`_' CHANGELOG.rst | sed -re 's@^`#([0-9]+)`_$@.. _#\1: https://github.com/jordansissel/fpm/issues/\1@' | sort -u > docs/changelog_links.rst
```
This finds all \`#NNN\`_ entries in the CHANGELOG.rst and puts it sorted
into changelog_links.rst for reStructuredText linking.