Apply suggestion from @BillWagner

Co-authored-by: Bill Wagner <wiwagn@microsoft.com>

Author: jskeet

standard/expressions.md

@@ -3880,6 +3880,7 @@ switch_expression_arm_expression
 ```
 
 The type of a *switch_expression* is the best common type [§12.6.3.16](expressions.md#126316-finding-the-best-common-type-of-a-set-of-expressions)) of the *switch_expression_arm_expression*s of the *switch_expression_arm*s, if such a type exists, and if each *switch_expression_arm_expression* can be implicitly converted to that type. Otherwise, the *switch_expression* has no type, but may still be subject to *switch expression conversions* ([§10.2.18](conversions.md#10218-switch-expression-conversion)).
+<-- The best common type is the "natural type" when we add natural types for lambda expressions and other typeless expressions -->
 
 It is an error if the pattern of any *switch_expression_arm* is *subsumed* by ([§11.1](patterns.md#111-general)) the set of patterns of earlier *unguarded* ([§13.8.3](statements.md#1383-the-switch-statement)) *switch_expression_arm*s of the switch expression.