Fix some pod syntax issues

C<<>> is legal, but empty. We want the code to show <>

Author: coke

doc/Language/5to6-nutshell.rakudoc

@@ -1142,7 +1142,7 @@ For lookaround assertions:
 
 For more info see L«lookahead assertions|/language/regexes#Lookahead_assertions».
 
-(Unrelated to C<<>> syntax, the "lookaround" C</foo\Kbar/> becomes C«/foo <( bar )> /»
+(Unrelated to C«<>» syntax, the "lookaround" C</foo\Kbar/> becomes C«/foo <( bar )> /»
 
 =item C<(?(?{condition))yes-pattern|no-pattern)> becomes C«[ <?{condition}>
       yes-pattern | no-pattern ]»

doc/Language/rb-nutshell.rakudoc

@@ -817,7 +817,7 @@ in Raku regexes.
 / "this is a test" /;           # Raku, quoting the whole string
 / this .* /;                    # Raku, possibly interesting string
 
-=head2 Special matchers generally fall under the C<<>> syntax
+=head2 Special matchers generally fall under the C«<>» syntax
 
 There are many cases of special matching syntax that Raku regexes support.
 They won't all be listed here, but often instead of being surrounded by C<()>,
@@ -849,7 +849,7 @@ For look-around assertions:
 
 =item C«(?<!ar?bitrary* pattern)» becomes C«<!after ar?bitrary* pattern>»
 
-(Unrelated to C<<>> syntax, the "lookaround" C</foo\Kbar/> becomes C«/foo <( bar )> /»
+(Unrelated to C«<>» syntax, the "lookaround" C</foo\Kbar/> becomes C«/foo <( bar )> /»
 
 =item C<(?(?{condition))yes-pattern|no-pattern)> becomes C«[ <?{condition}>
       yes-pattern | no-pattern ]»