Fix an incorrect example and a whitespace error in Str.pod

Author: Geoffrey Broadwell

lib/Str.pod

@@ -139,7 +139,7 @@ Examples:
     say index "Camelia is a butterfly", "Camel"; # 0
     say index "Camelia is a butterfly", "Onion"; # Int()
 
-    say index("Camelia is a butterfly", "Onion") ?? 'OK' !! 'NOT'; # NOT
+    say index("Camelia is a butterfly", "Onion").defined ?? 'OK' !! 'NOT'; # NOT
 
 =head2 rindex
 
@@ -218,8 +218,7 @@ Examples:
     lines("a\nb").perl;    # ("a", "b").list
     lines("a\nb").elems;   # 2
     "a\nb".lines.elems;    # 2
-
-	"a\n".lines.elems;     # 1
+    "a\n".lines.elems;     # 1
 
 =head2 words