User facing documentation

Documentation for mod_pagespeed and ngx_pagespeed is in mod_pagespeed/html/doc and is served from modpagespeed.com/doc. It's almost all static html, except that it uses server-side includes for the headers and footers. This means as long as you're not working on those you can do development by just loading the docs in a web browser off the file system.

In general, any change you make that goes beyond fixing a bug should have a documentation change in the same pull request. People need to be able to understand how both old and new versions work, however, so you should label your change "As of UNRELEASED". Then when the next release happens and the person doing the release will change "UNRELEASED" to something like "1.12.34.1" to indicate the first released version with the changes. We typically keep notes on doc usage around for at least a year after a version stops being supported. For example, as of 2017-01-10 the oldest notes we have in the doc are for 1.9, which we released on 2014-09-16 and has been unsupported since mid 2016. Notes for 1.8 aren't present anymore, since it has been unsupported for nearly two years.

To deploy doc changes, see deploying user-facing doc changes.