Add details in README files

Author: EmandM

com.unity.netcode.gameobjects/Tests/Editor/DocumentationCodeSamples/README.md

@@ -3,3 +3,29 @@
 Use this folder for any code snippets that only need to compile.
 
 Any code snippets that you want to run tests on should be put in [Runtime tests](../../Runtime/Documentation/README.md).
+
+To embed code in documentation, use the following tag
+
+```md
+[!code-cs[](../../Tests/Editor/DocumentationCodeSamples/<Path/To/Test>.cs#SomeRegionName)]
+```
+
+With the code formatted like this
+
+```cs
+namespace DocumentationCodeSamples
+{
+    internal MyTestClass
+    {
+        #region SomeRegionName
+        // All the code in this region block will be embedded without indentation in the docs.
+        #endregion
+
+        [Test]
+        public void TestOfDocumentationCode()
+        {
+            ...
+        }
+    }
+}
+```

com.unity.netcode.gameobjects/Tests/Runtime/DocumentationCodeSamples/README.md

@@ -3,3 +3,31 @@
 Use this folder for any code examples that we want to test to ensure the runtime functionality isn't broken
 
 Any code snippets that are small enough that you only want to check that they compile should be in [Editor tests](../../Editor/Documentation/README.md).
+
+To embed code in documentation, use the following tag
+
+```md
+[!code-cs[](../../Tests/Runtime/DocumentationCodeSamples/<Path/To/Test>.cs#SomeRegionName)]
+```
+
+With the code formatted like this
+
+```cs
+namespace DocumentationCodeSamples
+{
+    internal MyTestClass : NetcodeIntegrationTest
+    {
+        #region SomeRegionName
+        // All the code in this region block will be embedded without indentation in the docs.
+        #endregion
+
+        protected override int NumberOfClients => 1;
+
+        [UnityTest]
+        public IEnumerator TestOfDocumentationCode()
+        {
+            ...
+        }
+    }
+}
+```