Attempt to document Bool.gist

gistfile1.txt

=head2 routine gist

    multi method gist(Bool:D) returns Str:D
    multi method gist(Bool:U) returns Str:D

Returns a L<Str|/type/Str> representation of the invocant unless called on the
type object, in which case C<(Bool)>, i.e. the type name in parenthesis, is
returned instead.

    say Bool.gist;                                    # (Bool)
    say True.gist;                                    # True
    say False.gist;                                   # False