Add code example for CA1707 rule (#48934)

docs/fundamentals/code-analysis/quality-rules/ca1707.md

@@ -10,6 +10,8 @@ helpviewer_keywords:
 - IdentifiersShouldNotContainUnderscores
 author: gewarren
 ms.author: gewarren
+dev_langs:
+- CSharp
 ---
 # CA1707: Identifiers should not contain underscores
 
@@ -35,6 +37,10 @@ Naming conventions provide a common look for libraries that target the common la
 
 Remove all underscore characters from the name.
 
+## Example
+
+:::code language="csharp" source="snippets/csharp/all-rules/ca1707.cs" id="snippet1":::
+
 ## When to suppress warnings
 
 Do not suppress warnings for production code. However, it's safe to suppress this warning for test code.

docs/fundamentals/code-analysis/quality-rules/snippets/csharp/all-rules/ca1707.cs

@@ -0,0 +1,35 @@
+using System;
+
+// <Snippet1>
+// This code violates the rule.
+namespace ca_1707
+{
+    public interface IUser_Service
+    {
+        void Add_User(User_Model user_Model);
+    }
+
+    public class User_Service : IUser_Service
+    {
+        public const string Admin_Name = "admin";
+        public event EventHandler? User_Added;
+
+        public void Add_User(User_Model user_Model)
+        {
+            // ...
+        }
+    }
+
+    public struct User_Model
+    {
+        public int User_Id { get; set; }
+    }
+
+    public enum User_Type
+    {
+        Client_User = 0,
+        Manager_Admin = 1,
+        Syper_Admin = 3,
+    }
+}
+// </Snippet1>