reflect that type and const parameter can be intermixed

Also, add reference id

Author: tshepang

tests/ui/const-generics/argument_order.rs

@@ -1,15 +1,17 @@
-struct Bad<const N: usize, T> {
+//@ reference: items.generics.syntax.decl-order
+
+struct Good<const N: usize, T> {
     arr: [u8; { N }],
     another: T,
 }
 
-struct AlsoBad<const N: usize, 'a, T, 'b, const M: usize, U> {
+struct Bad<const N: usize, 'a, T, 'b, const M: usize, U> {
     //~^ ERROR lifetime parameters must be declared prior
     a: &'a T,
     b: &'b U,
 }
 
 fn main() {
-    let _: AlsoBad<7, 'static, u32, 'static, 17, u16>;
+    let _: Bad<7, 'static, u32, 'static, 17, u16>;
     //~^ ERROR lifetime provided when a type was expected
  }

tests/ui/const-generics/argument_order.stderr

@@ -1,14 +1,14 @@
 error: lifetime parameters must be declared prior to type and const parameters
-  --> $DIR/argument_order.rs:6:32
+  --> $DIR/argument_order.rs:8:28
    |
-LL | struct AlsoBad<const N: usize, 'a, T, 'b, const M: usize, U> {
-   |               -----------------^^-----^^-------------------- help: reorder the parameters: lifetimes, then consts and types: `<'a, 'b, const N: usize, T, const M: usize, U>`
+LL | struct Bad<const N: usize, 'a, T, 'b, const M: usize, U> {
+   |           -----------------^^-----^^-------------------- help: reorder the parameters: lifetimes, then consts and types: `<'a, 'b, const N: usize, T, const M: usize, U>`
 
 error[E0747]: lifetime provided when a type was expected
-  --> $DIR/argument_order.rs:13:23
+  --> $DIR/argument_order.rs:15:19
    |
-LL |     let _: AlsoBad<7, 'static, u32, 'static, 17, u16>;
-   |                       ^^^^^^^
+LL |     let _: Bad<7, 'static, u32, 'static, 17, u16>;
+   |                   ^^^^^^^
    |
    = note: lifetime arguments must be provided before type arguments
    = help: reorder the arguments: lifetimes, then type and consts: `<'a, 'b, N, T, M, U>`