add style for hanging indent

When trying to document a screen, answer choices, etc., it's often useful to have a hanging indent, that is a paragraph format where the first line sticks out and all remaining lines are indented:

Entry name: Here is elaboration on this entry but
     the elaboration that continues on the next line is indented
     as are all subsequent lines.

Next entry: using hanging indents makes it much faster to 
     visiually scan down a page to find the subsections.

All sorts of cases in documentation when this is useful