move RequiresSuper analyzer into apple subdir, add doc for RequiresSuper analyzer

XIA1004.md

@@ -0,0 +1,24 @@
+# XIA1004
+
+## Cause
+
+Overriding a method that requires a call to the overridden method
+
+## Rule description
+
+Notifies you when overriding a method with the `[RequiresSuper]` attribute
+
+## How to fix violations
+
+Apply the provided code fix to add base method call to overriding methods with the [RequiresSuper] attribute
+
+## How to suppress violations
+
+```csharp
+[System.Diagnostics.CodeAnalysis.SuppressMessage("Notifications", "XI0004RequiresSuperAttribute:Add base method call to methods with the [RequiresSuper] attribute", Justification = "<Pending>")]
+```
+
+```csharp
+#pragma warning disable XI0004RequiresSuperAttribute // Add base method call to methods with the [RequiresSuper] attribute
+#pragma warning restore XI0004RequiresSuperAttribute // Add base method call to methods with the [RequiresSuper] attribute
+```

src/Xamarin.CodeAnalysis/Apple/XIA1004RequiresSuper.cs

@@ -32,6 +32,8 @@ namespace Xamarin.CodeAnalysis
     public class XIA1004RequiresSuper : DiagnosticAnalyzer
     {
         public static readonly string DiagnosticId = "XI0004RequiresSuperAttribute";
+        const string HelpLink = "https://github.com/xamarin/CodeAnalysis/blob/master/docs/XIA1004.md";
+
 
         static readonly DiagnosticDescriptor Rule =
         new DiagnosticDescriptor(
@@ -40,7 +42,8 @@ namespace Xamarin.CodeAnalysis
             "Overriding the {0} method requires a call to the overridden method",
             "Notifications",
             DiagnosticSeverity.Info,
-            isEnabledByDefault: true
+            isEnabledByDefault: true,
+            HelpLink
             );
 
         public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(Rule);