fix grammar & remove reference to quoting

The remark that «» quotes are "also a valid quoting construct in Raku" is more confusing here, since the quoting construct semantics are very different from how they're used in "OUTPUT: «...»" comments.

Author: schultzdavid

doc/Language/intro.rakudoc

@@ -72,8 +72,8 @@ my @a = 1, 2, 3;
 say @a;             # OUTPUT: «[2 3 4]␤»
 
 Note on the last line, there is a comment, starting with C<# OUTPUT:>, that shows what the example outputs.
-The output is wrapped in C<«»> quotes (also a valid quoting construct in Raku!), and may include a C<␤>, which
-is the Unicode character "Symbol for Newline" - to indicates where in the actual output a literal newline would
+The output is wrapped in C<«»> quotes and may include a C<␤>, which
+is the Unicode character "Symbol for Newline", to indicate where in the actual output a literal newline would
 appear.
 
 =end item