Correct precedence of the null-conditional operators (#18037)

* Separate precedence for the null-conditional operators

* Addressed feedback

Author: pkulikov

docs/csharp/language-reference/operators/index.md

@@ -1,6 +1,6 @@
 ---
 title: "C# operators - C# reference"
-ms.date: 04/22/2020
+ms.date: 04/28/2020
 f1_keywords: 
   - "cs.operators"
 helpviewer_keywords: 
@@ -36,8 +36,8 @@ The following table lists the C# operators starting with the highest precedence
 
 | Operators | Category or name |
 | --------- | ---------------- |
-| [x.y](member-access-operators.md#member-access-expression-), [f(x)](member-access-operators.md#invocation-expression-), [a[i]](member-access-operators.md#indexer-operator-), [x++](arithmetic-operators.md#increment-operator-), [x--](arithmetic-operators.md#decrement-operator---), [x!](null-forgiving.md), [new](new-operator.md), [typeof](type-testing-and-cast.md#typeof-operator), [checked](../keywords/checked.md), [unchecked](../keywords/unchecked.md), [default](default.md), [nameof](nameof.md), [delegate](delegate-operator.md), [sizeof](sizeof.md), [stackalloc](stackalloc.md), [x->y](pointer-related-operators.md#pointer-member-access-operator--) | Primary |
-| [+x](arithmetic-operators.md#unary-plus-and-minus-operators), [-x](arithmetic-operators.md#unary-plus-and-minus-operators), [\!x](boolean-logical-operators.md#logical-negation-operator-), [~x](bitwise-and-shift-operators.md#bitwise-complement-operator-), [++x](arithmetic-operators.md#increment-operator-), [--x](arithmetic-operators.md#decrement-operator---), [^x](member-access-operators.md#index-from-end-operator-), [x?.y](member-access-operators.md#null-conditional-operators--and-), [x?[y]](member-access-operators.md#null-conditional-operators--and-), [(T)x](type-testing-and-cast.md#cast-expression), [await](await.md), [&x](pointer-related-operators.md#address-of-operator-), [*x](pointer-related-operators.md#pointer-indirection-operator-), [true and false](true-false-operators.md) | Unary |
+| [x.y](member-access-operators.md#member-access-expression-), [f(x)](member-access-operators.md#invocation-expression-), [a[i]](member-access-operators.md#indexer-operator-), [`x?.y`](member-access-operators.md#null-conditional-operators--and-), [`x?[y]`](member-access-operators.md#null-conditional-operators--and-), [x++](arithmetic-operators.md#increment-operator-), [x--](arithmetic-operators.md#decrement-operator---), [x!](null-forgiving.md), [new](new-operator.md), [typeof](type-testing-and-cast.md#typeof-operator), [checked](../keywords/checked.md), [unchecked](../keywords/unchecked.md), [default](default.md), [nameof](nameof.md), [delegate](delegate-operator.md), [sizeof](sizeof.md), [stackalloc](stackalloc.md), [x->y](pointer-related-operators.md#pointer-member-access-operator--) | Primary |
+| [+x](arithmetic-operators.md#unary-plus-and-minus-operators), [-x](arithmetic-operators.md#unary-plus-and-minus-operators), [\!x](boolean-logical-operators.md#logical-negation-operator-), [~x](bitwise-and-shift-operators.md#bitwise-complement-operator-), [++x](arithmetic-operators.md#increment-operator-), [--x](arithmetic-operators.md#decrement-operator---), [^x](member-access-operators.md#index-from-end-operator-), [(T)x](type-testing-and-cast.md#cast-expression), [await](await.md), [&x](pointer-related-operators.md#address-of-operator-), [*x](pointer-related-operators.md#pointer-indirection-operator-), [true and false](true-false-operators.md) | Unary |
 | [x..y](member-access-operators.md#range-operator-) | Range |
 | [switch](../../whats-new/csharp-8.md#switch-expressions) | `switch` expression |
 | [x * y](arithmetic-operators.md#multiplication-operator-), [x / y](arithmetic-operators.md#division-operator-), [x % y](arithmetic-operators.md#remainder-operator-) | Multiplicative|