Merge pull request #8792 from eiriktsarpalis/update-addcontext-docs

Update JsonSerializerOptions.AddContext documentation.

Author: eiriktsarpalis

xml/System.Text.Json.Serialization.Metadata/JsonTypeInfoResolver.xml

@@ -63,7 +63,7 @@ Can be used to combine multiple <xref:System.Text.Json.Serialization.JsonSeriali
           ]]></format>
         </remarks>
         <exception cref="T:System.ArgumentException">
-          <paramref name="resolvers" /> or any of its elements is <see langword="null" />.</exception>
+          <paramref name="resolvers" /> is <see langword="null" />.</exception>
       </Docs>
     </Member>
   </Members>

xml/System.Text.Json/JsonSerializerOptions.xml

@@ -126,14 +126,17 @@ For more information, see [How to serialize and deserialize JSON](/dotnet/standa
       <Parameters />
       <Docs>
         <typeparam name="TContext">The generic definition of the specified context type.</typeparam>
-        <summary>Binds current <see cref="T:System.Text.Json.JsonSerializerOptions" /> instance with a new instance of the specified <see cref="T:System.Text.Json.Serialization.JsonSerializerContext" /> type.</summary>
+        <summary>Appends a new <see cref="T:System.Text.Json.Serialization.JsonSerializerContext" /> to the metadata resolution of the current <see cref="T:System.Text.Json.JsonSerializerOptions" /> instance.</summary>
         <remarks>
           <format type="text/markdown"><![CDATA[
 
 ## Remarks
 
 When serializing and deserializing types using the options instance, metadata for the types will be fetched from the context instance.
 
+The methods supports adding multiple contexts per options instance. Metadata will be resolved in the order of configuration, 
+similar to how <xref:System.Text.Json.Serialization.Metadata.JsonTypeInfoResolver.Combine /> resolves metadata.
+
           ]]></format>
         </remarks>
       </Docs>