Add hacking.xml to the distribution

Dependencies

• [2] PKE6I67S doc: Import the "Creating Projects" chapter by Visser & Dolstra.
• [3] FV2M6MOT hydra: use autoconf/-make

Change contents

• replacement in doc/manual/Makefile.am at line 1
  [3.16946]→[2.0:74](∅→∅)
  − DOCBOOK_FILES = installation.xml introduction.xml manual.xml projects.xml
  [3.16946]

  [3.17008]
  + DOCBOOK_FILES = installation.xml introduction.xml manual.xml projects.xml hacking.xml