Definning the three stooges of categories

iffie, diffie and fiddly. Defined according to copied IRC chat from
@TimToady as transcribed by @kalkin in #728

Definitely not contributed to clean up the page, rather the obverse,
but I'm all in for cleaning, dirtying, or whatever is decided about
this page.

Author: JJ

doc/Language/glossary.pod6

@@ -228,7 +228,8 @@ See also L<https://en.wikipedia.org/wiki/Damian_Conway>.
 =head1 diffy
 X<|diffy>
 
-See L<operator|#Operator>.
+See L<operator|#Operator>. It means the type of the operator result is
+sufficiently different from its arguments that op= makes little sense
 
 =head1 Exegesis
 X<|Exegesis>
@@ -240,15 +241,15 @@ historical document for reference.  See also L<#Synopsis>.
 =head1 fiddly
 X<|fiddly>
 
-See L<operator|#Operator>.
+Too complicated to apply a metaop to. See L<operator|#Operator>.
 
 =head1 handles
 X<|handles>
 
 =head1 iffy
 X<|iffy>
 
-See L<operator|#Operator>.
+Often used as a boolean value. See L<operator|#Operator>.
 
 
 =head1 Instance