Fix pseudocode typo in RFC 1951

Phlosioneer · web-flow · commit 702798f50bb6 · 2018-03-22T01:21:42.000-04:00
I believe this `Whatever` was accidentally left out.
diff --git a/text/1951-expand-impl-trait.md b/text/1951-expand-impl-trait.md
@@ -222,7 +222,7 @@ fn foo<T, U>(t: T, u: U) where
 
 fn foo(
     t: impl Whatever + SomethingElse,
-    u: impl,
+    u: impl Whatever,
 )
 ```
 

Original file line number	Diff line number	Diff line change
`@@ -222,7 +222,7 @@ fn foo<T, U>(t: T, u: U) where`
`222`	`222`
`223`	`223`	`fn foo(`
`224`	`224`	`t: impl Whatever + SomethingElse,`
`225`		`- u: impl,`
	`225`	`+ u: impl Whatever,`
`226`	`226`	`)`
`227`	`227`	```
`228`	`228`