Use 0-based idx for array content

Author: cyqsimon

library/core/src/option.rs

@@ -1216,10 +1216,10 @@ impl<T> Option<T> {
     /// Often used to chain fallible operations that may return [`None`].
     ///
     /// ```
-    /// let arr_2d = [["A1", "A2"], ["B1", "B2"]];
+    /// let arr_2d = [["A0", "A1"], ["B0", "B1"]];
     ///
     /// let item_0_1 = arr_2d.get(0).and_then(|row| row.get(1));
-    /// assert_eq!(item_0_1, Some(&"A2"));
+    /// assert_eq!(item_0_1, Some(&"A1"));
     ///
     /// let item_2_0 = arr_2d.get(2).and_then(|row| row.get(0));
     /// assert_eq!(item_2_0, None);