changed-features/eta-expansion-spec.md : add expected type to example

Current code produces compilation error: 
"missing argument list for method foo"
The example requires an expected type to compile

Author: unkarjedy

docs/_docs/reference/changed-features/eta-expansion-spec.md

@@ -48,7 +48,7 @@ Methods with implicit parameter lists will always get applied to implicit argume
 def foo(x: Int)(implicit p: Double): Float = ???
 implicit val bla: Double = 1.0
 
-val bar = foo // val bar: Int => Float = ...
+val bar: Int => Float = foo // val bar: Int => Float = ...
 ```
 
 ## Automatic Eta-Expansion and context types