Add readme for sql server (#30466)

Co-authored-by: Lynn Dai <[email protected]>
Co-authored-by: Arthur Vickers <[email protected]>

Author: 3 people

src/EFCore.SqlServer/README.md

@@ -0,0 +1,39 @@
+Microsoft.EntityFrameworkCore.SqlServer is the database provider for Microsoft SQL Server and Azure SQL. This providers allows you to use Entity Framework Core with Microsoft SQL Server and Azure SQL databases.
+
+## Getting started
+
+`Microsoft.EntityFrameworkCore.Design` contains all the design-time logic for Entity Framework Core. It's the code that all of the various tools (PMC cmdlets like `Add-Migration`, `dotnet ef` & `ef.exe`) call into.
+
+If you don't use Migrations or Reverse Engineering, you don't need it.
+
+And when you do need it, we encourage `PrivateAssets="All" `so it doesn't get published to the server where you almost certainly won't need it.
+
+### Prerequisites
+
+- Supported database Engines: Microsoft SQL Server (2012 onwards)
+- The provider references Microsoft.Data.SqlClient (not System.Data.SqlClient). If your project takes a direct dependency on SqlClient, make sure it references the Microsoft.Data.SqlClient package.
+
+## Usage
+
+Once you've installed the package, you can use it in your Entity Framework Core application by specifying the SQL Server provider in your DbContext's OnConfiguring method:
+
+```csharp
+protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+{
+    optionsBuilder.UseSqlServer("Server=(localdb)\\mssqllocaldb;Database=MyDatabase;Trusted_Connection=True;");
+}
+```
+
+In this example, we're using the (localdb)\mssqllocaldb server with the MyDatabase database. You'll need to adjust the connection string to match your own SQL Server instance and database.
+
+## Features
+
+The SQL Server provider  supports all common features of [Entity Framework Core](https://learn.microsoft.com/ef/core/) as well as some [SQL Server-specific features](https://learn.microsoft.com/ef/core/providers/sql-server/?tabs=dotnet-core-cli) including temporal tables and memory-optimized tables.
+
+## Additional documentation
+
+For more information on using the SQL Server provider for Entity Framework Core, you can refer to the official [documentation](https://learn.microsoft.com/en-us/ef/core/providers/sql-server/?tabs=dotnet-core-cli).
+
+## Feedback
+
+If you encounter a bug or would like to request a feature, [submit an Github issue](https://github.com/dotnet/efcore/issues/new/choose). For more details, see [getting support](https://github.com/dotnet/efcore/blob/main/.github/SUPPORT.md).