Git ignore file seems overly broad

[mk-pmb]

Hi! We should make all the file patterns in .gitignore start with a slash, in order to make it predictable where they match. Example:

$ mkdir yolo
$ mkdir yolo/cover
$ touch yolo/cover/ohno
$ git status yolo/
On branch implement-yolo
nothing to commit, working tree clean

… which may cause accidential data loss in the ohno file. (Because the cover/ ignore rule matches in all subdirectories.)

The .history line should have a comment that describes it saves the prompt history, without replies.