Update known problems

Author: Henri Lunnikivi

clippy_lints/src/field_reassign_with_default.rs

@@ -15,7 +15,7 @@ declare_clippy_lint! {
     ///
     /// **Why is this bad?**It's more idiomatic to use the [functional update syntax](https://doc.rust-lang.org/reference/expressions/struct-expr.html#functional-update-syntax).
     ///
-    /// **Known problems:** None.
+    /// **Known problems:** Assignments to patterns that are of tuple type are not linted.
     ///
     /// **Example:**
     /// Bad: