README.packaging: List also tools as libfreeciv users
README.packaging chapter about shared libfreeciv says: "Libfreeciv contains code common to server and client." Update that to include tools (freeciv-manual, freeciv-mp-<gui>, freeciv-ruleup, freeciv-ruledit) too.
README.packaging chapter about shared libfreeciv says: "Libfreeciv contains code common to server and client." Update that to include tools (freeciv-manual, freeciv-mp-<gui>, freeciv-ruleup, freeciv-ruledit) too.