[ANN] kramdown 1.13.2 released

## About kramdown

kramdown (sic, not Kramdown or KramDown, just kramdown) is a *free*
MIT-licensed [Ruby](http://www.ruby-lang.org) library for parsing a
superset of Markdown.

It is completely written in Ruby, supports standard Markdown (with some
minor modifications) and various extensions that have been made popular
by the PHP Markdown Extra package and Maruku.

Homepage for installation instructions and documentation:

## kramdown 1.13.2 released

This release fixes some minor issues - updating is recommended.

## Changes

* 3 bug fixes:

  - Fix footnote link spacing to use non-breaking space (pull request
    [#399] by Martyn Chamberlin)
  - Show warning for unreferenced footnote definitions (fixes [#400]
    reported by Kyle Barbour)
  - Fix test cases with respect to Ruby 2.4 (fixes [#401] reported by
    Connor Shea)

[#399]: https://github.com/gettalong/kramdown/pull/399
[#400]: https://github.com/gettalong/kramdown/issues/400
[#401]: https://github.com/gettalong/kramdown/pull/401