Document Mono-specific classes

doc/classes/Texture.xml

 <?xml version="1.0" encoding="UTF-8" ?>
 <class name="Texture" inherits="Resource" version="4.0">
 	<brief_description>
+		The global C# namespace (Mono-enabled builds only).
 	</brief_description>
 	<description>
+		This class represents the global C# namespace. It is the C# equivalent of [@GDScript] and is only available in Mono-enabled builds.
+		See also [CSharpScript] and [GodotSharp].
 	</description>
 	<tutorials>
+		<link>https://docs.godotengine.org/en/latest/getting_started/scripting/c_sharp/index.html</link>
 	</tutorials>
 	<methods>
 	</methods>

modules/mono/doc_classes/CSharpScript.xml

 <?xml version="1.0" encoding="UTF-8" ?>
 <class name="CSharpScript" inherits="Script" version="4.0">
 	<brief_description>
+		A script implemented in the C# programming language (Mono-enabled builds only).
 	</brief_description>
 	<description>
+		This class represents a C# script. It is the C# equivalent of the [GDScript] class and is only available in Mono-enabled Godot builds.
+		See also [GodotSharp].
 	</description>
 	<tutorials>
+		<link>https://docs.godotengine.org/en/latest/getting_started/scripting/c_sharp/index.html</link>
 	</tutorials>
 	<methods>
 		<method name="new" qualifiers="vararg">
 			<return type="Variant">
 			</return>
 			<description>
+				Returns a new instance of the script.
 			</description>
 		</method>
 	</methods>

modules/mono/doc_classes/GodotSharp.xml

 <?xml version="1.0" encoding="UTF-8" ?>
 <class name="GodotSharp" inherits="Object" version="4.0">
 	<brief_description>
+		Bridge between Godot and the Mono runtime (Mono-enabled builds only).
 	</brief_description>
 	<description>
+		This class is a bridge between Godot and the Mono runtime. It exposes several low-level operations and is only available in Mono-enabled Godot builds.
+		See also [CSharpScript].
 	</description>
 	<tutorials>
 	</tutorials>
@@ -11,26 +14,30 @@
 			<return type="void">
 			</return>
 			<description>
-				Attaches the current thread to the mono runtime.
+				Attaches the current thread to the Mono runtime.
 			</description>
 		</method>
 		<method name="detach_thread">
 			<return type="void">
 			</return>
 			<description>
-				Detaches the current thread from the mono runtime.
+				Detaches the current thread from the Mono runtime.
 			</description>
 		</method>
 		<method name="get_domain_id">
 			<return type="int">
 			</return>
 			<description>
+				Returns the current MonoDomain ID.
+				[b]Note:[/b] The Mono runtime must be initialized for this method to work (use [method is_runtime_initialized] to check). If the Mono runtime isn't initialized at the time this method is called, the engine will crash.
 			</description>
 		</method>
 		<method name="get_scripts_domain_id">
 			<return type="int">
 			</return>
 			<description>
+				Returns the scripts MonoDomain's ID. This will be the same MonoDomain ID as [method get_domain_id], unless the scripts domain isn't loaded.
+				[b]Note:[/b] The Mono runtime must be initialized for this method to work (use [method is_runtime_initialized] to check). If the Mono runtime isn't initialized at the time this method is called, the engine will crash.
 			</description>
 		</method>
 		<method name="is_domain_finalizing_for_unload">
@@ -39,26 +46,28 @@
 			<argument index="0" name="domain_id" type="int">
 			</argument>
 			<description>
-				Returns whether the domain is being finalized.
+				Returns [code]true[/code] if the domain is being finalized, [code]false[/code] otherwise.
 			</description>
 		</method>
 		<method name="is_runtime_initialized">
 			<return type="bool">
 			</return>
 			<description>
+				Returns [code]true[/code] if the Mono runtime is initialized, [code]false[/code] otherwise.
 			</description>
 		</method>
 		<method name="is_runtime_shutting_down">
 			<return type="bool">
 			</return>
 			<description>
+				Returns [code]true[/code] if the Mono runtime is shutting down, [code]false[/code] otherwise.
 			</description>
 		</method>
 		<method name="is_scripts_domain_loaded">
 			<return type="bool">
 			</return>
 			<description>
-				Returns whether the scripts domain is loaded.
+				Returns [code]true[/code] if the scripts domain is loaded, [code]false[/code] otherwise.
 			</description>
 		</method>
 	</methods>