Document a few atmos classes.

Content.Server/Atmos/Components/GasTankComponent.cs

@@ -1,4 +1,3 @@
-#nullable disable warnings
 using System;
 using Content.Server.Atmos.EntitySystems;
 using Content.Server.Body.Respiratory;

Content.Server/Atmos/Components/GridAtmosphereComponent.cs

@@ -14,13 +14,14 @@ using Dependency = Robust.Shared.IoC.DependencyAttribute;
 namespace Content.Server.Atmos.Components
 {
     /// <summary>
-    ///     This is our SSAir equivalent.
+    ///     Internal Atmos class. Use <see cref="AtmosphereSystem"/> to interact with atmos instead.
     /// </summary>
     [ComponentReference(typeof(IAtmosphereComponent))]
     [RegisterComponent, Serializable]
     public class GridAtmosphereComponent : Component, IAtmosphereComponent, ISerializationHooks
     {
         public override string Name => "GridAtmosphere";
+
         public virtual bool Simulated => true;
 
         [ViewVariables]

Content.Server/Atmos/EntitySystems/AtmosphereSystem.cs

@@ -8,6 +8,9 @@ using Robust.Shared.Map;
 
 namespace Content.Server.Atmos.EntitySystems
 {
+    /// <summary>
+    ///     This is our SSAir equivalent, if you need to interact with or query atmos in any way, go through this.
+    /// </summary>
     [UsedImplicitly]
     public partial class AtmosphereSystem : SharedAtmosphereSystem
     {

Content.Server/Atmos/TileAtmosphere.cs

@@ -1,3 +1,4 @@
+using Content.Server.Atmos.EntitySystems;
 using Content.Shared.Atmos;
 using Content.Shared.Maps;
 using Robust.Shared.Map;
@@ -8,6 +9,7 @@ namespace Content.Server.Atmos
 {
     /// <summary>
     ///     Internal Atmos class that stores data about the atmosphere in a grid.
+    ///     You shouldn't use this directly, use <see cref="AtmosphereSystem"/> instead.
     /// </summary>
     public class TileAtmosphere : IGasMixtureHolder
     {