Add E0369 error explanation

Author: GuillaumeGomez

src/librustc_typeck/diagnostics.rs

@@ -2585,6 +2585,28 @@ to change this.
 [RFC 953]: https://github.com/rust-lang/rfcs/pull/953
 "##,
 
+E0369: r##"
+A binary operation was attempted on a type which doesn't support it.
+Erroneous code example:
+
+```
+let x = 12f32; // error: binary operation `<<` cannot be applied to
+               //        type `f32`
+
+x << 2;
+```
+
+To fix this error, please check this type implements this binary operation.
+Example:
+
+```
+let x = 12u32; // the `u32` type does implement it:
+               // https://doc.rust-lang.org/stable/std/ops/trait.Shl.html
+
+x << 2; // ok!
+```
+"##,
+
 E0371: r##"
 When `Trait2` is a subtrait of `Trait1` (for example, when `Trait2` has a
 definition like `trait Trait2: Trait1 { ... }`), it is not allowed to implement
@@ -2773,7 +2795,6 @@ register_diagnostics! {
     E0325, // implemented an associated type when another trait item expected
     E0328, // cannot implement Unsize explicitly
     E0329, // associated const depends on type parameter or Self.
-    E0369, // binary operation `<op>` cannot be applied to types
     E0370, // discriminant overflow
     E0374, // the trait `CoerceUnsized` may only be implemented for a coercion
            // between structures with one field being coerced, none found