Document Tagcast 0.70.2 release and move shipped changes into guides
Document unreleased online source preferences
Document the released Tagcast 0.70.0 features
Document unreleased library metadata exports
Document optional cached album information in upcoming changes
Document upcoming artist profiles and interface changes Keep 0.60.0 instructions intact and label features from main as unreleased. Add the upcoming guide to the home page and sidebar, with links from affected topics.
Organize the Tagcast user guide by topic