Add static array indexing to example & mention bounds checks

Author: ntrel

spec/arrays.dd

@@ -182,6 +182,11 @@ assert(a[2] == 3);
 a[2] = 4;
 assert(a[2] == 4);
 assert(a == [1,2,4]);
+//writeln(a[3]); // runtime error (unless bounds checks turned off)
+
+int[2] b = [1,2];
+assert(b[1] == 2);
+//writeln(b[2]); // compile-time error, index out of bounds
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 )