Update documentation

Author: Matt Chaulklin

StyleCop.Analyzers/StyleCop.Analyzers/SpacingRules/SA1001CommasMustBeSpacedCorrectly.cs

@@ -30,7 +30,6 @@ internal class SA1001CommasMustBeSpacedCorrectly : DiagnosticAnalyzer
         /// The ID for diagnostics produced by the <see cref="SA1001CommasMustBeSpacedCorrectly"/> analyzer.
         /// </summary>
         public const string DiagnosticId = "SA1001";
-
         private const string HelpLink = "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/blob/master/documentation/SA1001.md";
         private static readonly LocalizableString Title = new LocalizableResourceString(nameof(SpacingResources.SA1001Title), SpacingResources.ResourceManager, typeof(SpacingResources));
         private static readonly LocalizableString MessageFormat = new LocalizableResourceString(nameof(SpacingResources.SA1001MessageFormat), SpacingResources.ResourceManager, typeof(SpacingResources));

documentation/SA1001.md

@@ -28,7 +28,7 @@ A comma should be followed by a single space, except in the following cases.
 * A comma may appear at the end of a line
 * A comma should not be followed by a space when used in an open generic type in a `typeof` expression
 * A comma is part of a string interpolation alignment component. For example:`$"{x,3}"`
-* A comma follows a preprocessor directive. For example:
+* A comma follows a conditional preprocessor directive (#if, #elif, #else, #endif). For example:
   ```csharp
   partial struct Money : IFormattable
   #if !NETSTANDARD