fix(ng-doc/example paths): use paths from configuration + configurable example paths

paths were hardcoded in the ngdoc: component group generator, updated to use the paths from the configuration (processing.api-docs).

this will only cause issues if you had changed processing.api-docs.path or processing.api-docs.outputPath and still expect the component groups to be output in the hardcoded location (which probably doesn't make sense?).

with default settings this will produce the same result.

edit: also updated paths used by components so they can be configured. 

This should be 'processing.component-groups' not 'api-docs'. That is a different processor with different configuration.