Create readme.txt (#33265)

* Create readme.txt

* Delete aspnetcore/data/ef-rp/intro/samples/cu80 directory

aspnetcore/data/ef-rp/intro/samples/cu80/PaginatedList.cs

@@ -1,36 +0,0 @@
-// See https://github.com/dotnet/AspNetCore.Docs/pull/28082
-// This code has been proposed but has not be tested.
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
-using Microsoft.EntityFrameworkCore;
-
-namespace ContosoUniversity
-{
-    public class PaginatedList<T> : List<T>
-    {
-        public PaginatedList(IEnumerable<T> items, int count, int pageIndex, int pageSize = 20)
-        {
-            PageIndex = pageIndex;
-            TotalPages = (int)Math.Ceiling(count / (double)pageSize);
-
-            this.AddRange(items);
-        }
-
-        public bool HasPreviousPage => PageIndex > 1;
-        public bool HasNextPage => PageIndex < TotalPages;
-        public int PageIndex { get; private set; }
-        public int TotalPages { get; private set; }
-
-        public static async Task<PaginatedList<T>> CreateAsync(
-            IQueryable<T> source, int pageIndex, int pageSize = 20)
-        {
-            var count = await source.CountAsync();
-            var items = await source.Skip(
-                (pageIndex - 1) * pageSize)
-                .Take(pageSize).ToListAsync();
-            return new PaginatedList<T>(items, count, pageIndex, pageSize);
-        }
-    }
-}

aspnetcore/data/ef-rp/intro/samples/cu80/appsettings.Development2.json

@@ -1,13 +0,0 @@
-{
-  "DetailedErrors": true,
-  "Logging": {
-    "LogLevel": {
-      "Default": "Information",
-      "Microsoft.AspNetCore": "Warning"
-    }
-  },
-  "ConnectionStrings": {
-    "SchoolContextSQLite": "Data Source=CU.db"
-  },
-  "MyMaxModelBindingCollectionSize": "3"
-}

aspnetcore/data/ef-rp/intro/samples/cu90/readme.txt

@@ -0,0 +1 @@
+Delete this readme file when the code has been updated to .NET 9