clarify abstractions conditional scope

docs/docs/getting-started/installation.mdx

@@ -60,8 +60,7 @@ Checkout the latest stable version [here](https://mapperly.riok.app).
 ### Preserving the attributes at runtime
 
 Mapperly removes the attribute references at compile time by default (they have the `ConditionalAttribute`).
-If you want
-to preserve the attribute references at runtime
+If you want to preserve the attribute references at runtime
 you can set the MSBuild variable `MapperlyAbstractionsScope` to `runtime`.
 
 ```xml
@@ -74,3 +73,12 @@ you can set the MSBuild variable `MapperlyAbstractionsScope` to `runtime`.
 When preserving the attribute usages, the Mapperly package reference needs to include the runtime assets.  
 Make sure `ExcludeAssets` on the `PackageReference` does not include `runtime`.
 :::
+
+:::info
+`MapperlyAbstractionsScope` only works in projects referencing `Riok.Mapperly` directly.
+Alternatively you can set a constant `MAPPERLY_ABSTRACTIONS_SCOPE_RUNTIME`:
+```xml
+<PropertyGroup>
+  <DefineConstants>$(DefineConstants);MAPPERLY_ABSTRACTIONS_SCOPE_RUNTIME</DefineConstants>
+</PropertyGroup>
+:::

src/Riok.Mapperly.Abstractions/MapperAttribute.cs

@@ -21,6 +21,12 @@ public class MapperAttribute : Attribute
     /// </summary>
     public EnumMappingStrategy EnumMappingStrategy { get; set; } = EnumMappingStrategy.ByValue;
 
+    /// <summary>
+    /// Defines the strategy to use when mapping an enum from/to string.
+    /// Can be overwritten on specific enums via mapping method configurations.
+    /// </summary>
+    public EnumNamingStrategy EnumNamingStrategy { get; set; } = EnumNamingStrategy.MemberName;
+
     /// <summary>
     /// Whether the case should be ignored for enum mappings.
     /// </summary>
@@ -125,10 +131,4 @@ public class MapperAttribute : Attribute
     /// partial methods are discovered.
     /// </summary>
     public bool AutoUserMappings { get; set; } = true;
-
-    /// <summary>
-    /// Defines the strategy to use when mapping an enum from/to string.
-    /// Can be overwritten on specific enums via mapping method configurations.
-    /// </summary>
-    public EnumNamingStrategy EnumNamingStrategy { get; set; } = EnumNamingStrategy.MemberName;
 }