Clean up E0070 long explanation

src/librustc_error_codes/error_codes/E0070.md

@@ -1,3 +1,26 @@
+An assignment operator was used on a non-place expression.
+
+Erroneous code examples:
+
+```compile_fail,E0070
+struct SomeStruct {
+    x: i32,
+    y: i32,
+}
+
+const SOME_CONST: i32 = 12;
+
+fn some_other_func() {}
+
+fn some_function() {
+    SOME_CONST = 14; // error: a constant value cannot be changed!
+    1 = 3; // error: 1 isn't a valid place!
+    some_other_func() = 4; // error: we cannot assign value to a function!
+    SomeStruct::x = 12; // error: SomeStruct a structure name but it is used
+                        //        like a variable!
+}
+```
+
 The left-hand side of an assignment operator must be a place expression. A
 place expression represents a memory location and can be a variable (with
 optional namespacing), a dereference, an indexing expression or a field
@@ -7,35 +30,14 @@ More details can be found in the [Expressions] section of the Reference.
 
 [Expressions]: https://doc.rust-lang.org/reference/expressions.html#places-rvalues-and-temporaries
 
-Now, we can go further. Here are some erroneous code examples:
-
-```compile_fail,E0070
-struct SomeStruct {
-    x: i32,
-    y: i32
-}
-
-const SOME_CONST : i32 = 12;
-
-fn some_other_func() {}
-
-fn some_function() {
-    SOME_CONST = 14; // error : a constant value cannot be changed!
-    1 = 3; // error : 1 isn't a valid place!
-    some_other_func() = 4; // error : we cannot assign value to a function!
-    SomeStruct.x = 12; // error : SomeStruct a structure name but it is used
-                       // like a variable!
-}
-```
-
 And now let's give working examples:
 
 ```
 struct SomeStruct {
     x: i32,
-    y: i32
+    y: i32,
 }
-let mut s = SomeStruct {x: 0, y: 0};
+let mut s = SomeStruct { x: 0, y: 0 };
 
 s.x = 3; // that's good !