vouch#439 honor DocumentRoot for error pages

Specify default is 5

link to local dev SPA example

vouch --> Vouch Proxy

vouch#373 VP "in a path"

fix vouch#304 add CHANGELOG.md

vouch#406 fix naming of alpine images, update README

Merge branch 'fix/docker_build_push_quay.io'

set cache expiration to jwt expiration