Revert "new_ret_no_self: add sample from #3313 to Known Problems section."

This reverts commit fd2f6dd382.

Issue #3313 has been fixed.

clippy_lints/src/methods/mod.rs

@@ -452,8 +452,7 @@ declare_clippy_lint! {
 /// **Why is this bad?** As a convention, `new` methods are used to make a new
 /// instance of a type.
 ///
-/// **Known problems:** The lint fires when the return type is wrapping `Self`.
-/// Example: `fn new() -> Result<Self, E> {}`
+/// **Known problems:** None.
 ///
 /// **Example:**
 /// ```rust