Fix typo

Author: lizmat

S99-glossary.pod

@@ -1941,10 +1941,9 @@ a wider, non-Perl 6 context, it can refer to any implicit conversion.
 
 A L</function>, </method> or L</op> is pure if it has no side effect,
 and the value it gives is depends only of its arguments so it is
-L</referential transparent|referentially transparent> givint the opportunity
+L</referential transparent|referentially transparent> giving the opportunity
 of optimizations.
 
-
 =head2 pure perl
 
 Use to qualify Some source code, or L</project> that does not depend