Merge branch 'jk/doc-config-include' into maint

Clarify documentation for include.path and includeIf.<condition>.path
configuration variables.

* jk/doc-config-include:
  docs/config: consistify include.path examples
  docs/config: avoid the term "expand" for includes
  docs/config: give a relative includeIf example
  docs/config: clarify include/includeIf relationship