Fix comments in example .gitignore file

The gitignore man page states that the lines starting with '#' are
ignored, but the sharp characters inside a line do not start a comment.
They are part of the regex. The comments must be seperated on their own line.
Merge pull request #393 from fernsehkind/master

[de] Improve german translation of chapter "Git Configruation" (7.1)
Merge pull request #392 from progit/fix_gitignore

Fix comments in example .gitignore file