Added a note about FGAddon and svn. The article gives the impression that FGAddon would also be a git repository.
'''Git''' is a version control system, used by the [[FlightGear]] project to store all of the files required to build and run FlightGear. This includes all the programs, the data (e.g. textures, sounds), supporting tools, etc. Git tracks updates to every file, as developers from around the world work together concurrently to create new versions.
While new FlightGear features and additions are in development, they are available from Git before they are available in the standard release version. Using Git allows users to use the newest possible version of FlightGear from the latest source files, to experiment with new aircraft or other features. However, it is not a beginner's tool. Using Git can expose the user to unstable features that show ugly error messages, or crash the computer.