Add a little bit about :sigspace

lib/Language/regexes.pod

@@ -332,4 +332,22 @@ TODO
 
 TODO
 
+=head1 Adverbs
+
+TODO
+
+=head2 Sigspace
+
+The B<C<:sigspace>> or B<C<:s>> adverb makes whitespace significant in a regex.
+
+    =begin code :allow<B>
+    say so "I used Photoshop®"  ~~ m:i/   photo shop /; # True
+    say so "I used a photo shop ~~ m:iB<:s>/ photo shop /; # True
+    say so "I used Photoshop®"  ~~ m:iB<:s>/ photo shop /; # False
+    =end code
+
+C<m:s/ photo shop /> acts just the same as if one had written C<m/ photo <ws>
+shop <ws> />. By default, C<< <ws> >> makes sure that words are seperated, so
+C<a    b> and C<^&> will match C<< <ws> >> in the middle, but C<ab> won't.
+
 =end pod