Fix header thinkos

Author: lizmat

doc/Language/glossary.pod

@@ -542,7 +542,7 @@ in Perl 6.  It is what C<self> refers to in a method.
     class A { method show { self } }
     say A.new.show;       # A.new
 
-=head2 JIT
+=head1 JIT
 
 =head1 Junction
 
@@ -664,7 +664,7 @@ See L<#Attribute>.
 A value that can be used on the right hand side of an assignment.  See also
 L<#lvalue>.
 
-=head2 Scalar
+=head1 Scalar
 
 =head1 Sigil
 
@@ -676,7 +676,7 @@ for L<variable interpolation#Variable Interpolation> in a double quoted
 string, or even L<postcircumfix|#Postcircumfix> L<expressions|#Expression>
 starting with such a variable.
 
-=head2 Sigilless Variable
+=head1 Sigilless Variable
 
 =head1 Slot