Clean up E0769 explanation

compiler/rustc_error_codes/src/error_codes/E0769.md

@@ -1,5 +1,5 @@
-A tuple struct or tuple variant was used in a pattern as if it were a
+A tuple struct or tuple variant was used in a pattern as if it were a struct or
-struct or struct variant.
+struct variant.
 
 Erroneous code example:
 
@@ -7,9 +7,13 @@ Erroneous code example:
 enum E {
     A(i32),
 }
+
 let e = E::A(42);
+
 match e {
-    E::A { number } => println!("{}", x),
+    E::A { number } => { // error!
+        println!("{}", number);
+    }
 }
 ```
 
@@ -21,12 +25,14 @@ To fix this error, you can use the tuple pattern:
 # }
 # let e = E::A(42);
 match e {
-    E::A(number) => println!("{}", number),
+    E::A(number) => { // ok!
+        println!("{}", number);
+    }
 }
 ```
 
-Alternatively, you can also use the struct pattern by using the correct
+Alternatively, you can also use the struct pattern by using the correct field
-field names and binding them to new identifiers:
+names and binding them to new identifiers:
 
 ```
 # enum E {
@@ -34,6 +40,8 @@ field names and binding them to new identifiers:
 # }
 # let e = E::A(42);
 match e {
-    E::A { 0: number } => println!("{}", number),
+    E::A { 0: number } => { // ok!
+        println!("{}", number);
+    }
 }
 ```