add documentation how to install server on ubuntu 20.04 and add server version stuff

MareSynchronosServer/MareSynchronosServer/Hubs/ConnectionHub.cs

@@ -1,4 +1,5 @@
 using System.Linq;
+using System.Runtime.ConstrainedExecution;
 using System.Security.Claims;
 using System.Threading.Tasks;
 using MareSynchronos.API;
@@ -10,11 +11,12 @@ namespace MareSynchronosServer.Hubs
 {
     public class ConnectionHub : BaseHub<ConnectionHub>
     {
+        private const int ServerVersion = 1;
         public ConnectionHub(MareDbContext mareDbContext, ILogger<ConnectionHub> logger) : base(mareDbContext, logger)
         {
         }
 
-        public async Task<LoggedInUserDto> Heartbeat()
+        public async Task<ConnectionDto> Heartbeat()
         {
             var userId = Context.User!.Claims.SingleOrDefault(c => c.Type == ClaimTypes.NameIdentifier)?.Value;
             
@@ -23,15 +25,16 @@ namespace MareSynchronosServer.Hubs
             {
                 Logger.LogInformation("Connection from " + userId);
                 var user = (await DbContext.Users.SingleAsync(u => u.UID == userId));
-                return new LoggedInUserDto
+                return new ConnectionDto
                 {
+                    ServerVersion = ServerVersion,
                     UID = userId,
                     IsModerator = user.IsModerator,
                     IsAdmin = user.IsAdmin
                 };
             }
 
-            return new LoggedInUserDto();
+            return new ConnectionDto();
         }
     }
 }