added basic xml comments to all Oqtane.Services interfaces

Oqtane.Client/Services/Interfaces/IDatabaseService.cs

@@ -4,8 +4,15 @@ using System.Threading.Tasks;
 
 namespace Oqtane.Services
 {
+    /// <summary>
+    /// Service to retrieve <see cref="Database"/> information.
+    /// </summary>
     public interface IDatabaseService
     {
+        /// <summary>
+        /// Returns a list of databases
+        /// </summary>
+        /// <returns></returns>
         Task<List<Database>> GetDatabasesAsync();
     }
 }