Document the reason for excluding certain expressions from analysis

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers/SpacingRules/SA1003SymbolsMustBeSpacedCorrectly.cs

@@ -270,6 +270,7 @@ private static void HandlePrefixUnaryExpression(SyntaxNodeAnalysisContext contex
             case SyntaxKind.MinusToken:
             case SyntaxKind.PlusPlusToken:
             case SyntaxKind.MinusMinusToken:
+                // These expressions are handled by SA1020, SA1021, SA1022
                 analyze = false;
                 break;