For example should be used instead while in WHILE_LET_ON_ITERATOR

`For` example should be used instead `while` in WHILE_LET_ON_ITERATOR

For example should be used instead while in WHILE_LET_ON_ITERATOR

Revert some changes

Fix cargo dev fmt

clippy_lints/src/loops/mod.rs

@@ -346,7 +346,14 @@
     ///
     /// ### Example
     /// ```ignore
-    /// while let Some(val) = iter() {
+    /// while let Some(val) = iter.next() {
+    ///     ..
+    /// }
+    /// ```
+    ///
+    /// Use instead:
+    /// ```ignore
+    /// for val in &mut iter {
     ///     ..
     /// }
     /// ```