Create update/changes page

[ianb]

Per #1869 we want to show users updates and changes periodically. We need a new page to host these changes.

It could probably be a static HTML page, as it won't have any dynamic features. It should be styled in an appropriate way. It could link to CHANGELOG.html (which may need some style fixes), as a "see complete list of changes" link.

This page should also be setup like an ejs page (to pull in headers/footers), similar to lexicon.