Updating code format rules for documentation comments.

Making it clear that the star-every-line style of documentation comment makes avrodoc unhappy. Also putting in that we ought to keep to 80 characters per line, since I think we ought to keep to 80 characters per line.
s/attribute/for attribute/
Demanding multi-line comment indentation.

Single line documentation comments /** like this */ aren't multi-line and are therefore fine.
Merge pull request #82 from adamnovak/styleGuide

Updating code format rules for documentation comments.