doc-src/Intro/bool.thy

For the new version of name_thm. Now the same theorem
is stored as is returned, as both contain a label and a link to the
previous derivation. So get_thm no longer needs to attach a label to
its resulting theorem.

Bool = FOL +
types 	bool 0
arities bool 	:: term
consts tt,ff	:: "bool"
end