Error and unused data cleanup

This merge request removes unused images as well the intro part which is not referenced anywhere and duplicates the content of other parts of the documentation.

It also fixes some errors with regard to broken links and method documentation duplication.

Related to beat.editor#258 (closed)

added bug enhancement labels

cc @andre.anjos

changed the description

merged

mentioned in commit e93323cf

Thx for the clean-up.