Fix charter 404

[scottrigby]

fixes #762

I think I did this right.

Test with:

$ git submodule update --init --recursive
$ npm install
$ npm run serve
$ curl -s http://localhost:1313/about/charter/ | grep -o '<h1.*</h1>'
<h1></h1><h1 id=cncf-tag-contributor-strategy-charter>CNCF TAG Contributor Strategy Charter</h1>

[jberkus]

Something weird is going on with the navigation, look as the directory on the left: