Update the CS1031 page (#47527)

* Update the CS1031 page and remove not needed code

* Improve the code example and emphasize on the type parameter

Author: BartoszKlonowski

docs/csharp/misc/cs1031.md

@@ -12,35 +12,32 @@ ms.assetid: 14196659-aaac-4df2-a4ed-0bebb8097d59
 
 Type expected  
 
- A type parameter is expected.  
-  
-## Example  
+A type has not been specified where expected, when [overloading an operator](../language-reference/operators/operator-overloading.md).
+<br/>Missing *type* in this case means that there's no *type* given for the return type of the overloaded operator.
+This error shouldn't be confused with missing [generic type parameter](../../csharp/programming-guide/generics/generic-type-parameters.md).
 
- The following sample generates CS1031:  
-  
-```csharp  
-// CS1031.cs  
-namespace x  
-{  
-    public class ii  
-    {  
-    }  
-  
-    public class a  
+## Example
+
+The following sample generates CS1031:
+
+```csharp
+namespace x
+{
+    public class I
+    {
+    }
+
+    public class A
     {  
-        public static operator +(a aa)   // CS1031  
-        // try the following line instead  
-        // public static ii operator +(a aa)  
-        {  
-            return new ii();  
-        }  
-  
-        public static void Main()  
-        {  
-            e = new base;   // CS1031, not a type  
-            e = new this;   // CS1031, not a type  
-            e = new ();     // CS1031, not a type  
-        }  
-    }  
-}  
+        public static operator +(A a)    // CS1031 - Overloaded operator missing a type
+        {
+            return new I();
+        }
+
+        public static I operator +(A a)  // Correct - type was specified
+        {
+            return new I();
+        }
+    }
+}
 ```