added basic xml comments to all Oqtane.Services interfaces

Oqtane.Client/Services/Interfaces/ISqlService.cs

@@ -1,10 +1,18 @@
-using Oqtane.Models;
+using Oqtane.Models;
 using System.Threading.Tasks;
 
 namespace Oqtane.Services
 {
+    /// <summary>
+    ///  Service to execute a <see cref="SqlQuery"/> against the backend database
+    /// </summary>
     public interface ISqlService
     {
+        /// <summary>
+        /// Executes a sql query and returns its result
+        /// </summary>
+        /// <param name="sqlquery"></param>
+        /// <returns></returns>
         Task<SqlQuery> ExecuteQueryAsync(SqlQuery sqlquery);
     }
 }