Merge branch 'nd/conditional-config-include'

The configuration file learned a new "includeIf.<condition>.path" that includes the contents of the given path only when the condition holds. This allows you to say "include this work-related bit only in the repositories under my ~/work/ directory". * nd/conditional-config-include: config: add conditional include config.txt: reflow the second include.path paragraph config.txt: clarify multiple key values in include.path