add xmldoc comments

web/backend/Database/Database.Seed/ISeeder.cs

@@ -2,7 +2,18 @@ using Microsoft.Data.SqlClient;
 
 namespace Database.Seed;
 
+/// <summary>
+/// Defines a unit of seed data that can be applied to the database. Implementations
+/// should be safe to run against an already-seeded database (e.g. by checking for
+/// existing data before inserting) and may depend on data created by seeders that run
+/// before them.
+/// </summary>
 internal interface ISeeder
 {
+    /// <summary>
+    /// Inserts this seeder's data into the database using the supplied open connection.
+    /// </summary>
+    /// <param name="connection">An open connection to the target database.</param>
+    /// <returns>A task that completes when seeding is finished.</returns>
     Task SeedAsync(SqlConnection connection);
 }