Add readme file for nuget package EFCore.Tools (#30470)

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

Author: lyndaidaii

src/EFCore.Tools/README.md

@@ -0,0 +1,41 @@
+The Entity Framework Core tools help with design-time development tasks. They're primarily used to manage Migrations and to scaffold a DbContext and entity types by reverse engineering the schema of a database.
+Microsoft.EntityFrameworkCore.Tools is for PowerShell tooling that works in the Visual Studio Package Manager Console.
+
+## Getting started
+
+The Package Manager Console (PMC) tools for Entity Framework Core perform design-time development tasks. For example, they create migrations, apply migrations, and generate code for a model based on an existing database. The commands run inside of Visual Studio using the Package Manager Console. These tools work with both .NET Framework and .NET Core projects.
+
+### Prerequisites
+
+Before using the tools:
+
+- [Understand the difference between target and startup project](https://learn.microsoft.com/en-us/ef/core/cli/powershell#target-and-startup-project).
+- [Learn how to use the tools with .NET Standard class libraries](https://learn.microsoft.com/en-us/ef/core/cli/powershell#other-target-frameworks).
+- [For ASP.NET Core projects, set the environment](https://learn.microsoft.com/en-us/ef/core/cli/powershell#aspnet-core-environment).
+
+## Usage
+
+PMC Command | Usage
+-- | --
+Get-Help entityframework |Displays information about entity framework commands.
+[Add-Migration](https://learn.microsoft.com/en-us/ef/core/cli/powershell#add-migration)  | Creates a migration by adding a migration snapshot.
+[Bundle-Migration](https://learn.microsoft.com/en-us/ef/core/cli/powershell#bundle-migration) | Creates an executable to update the database.
+[Get-DbContext](https://learn.microsoft.com/en-us/ef/core/cli/powershell#get-dbcontext) | Gets information about a DbContext type.
+[Drop-Database](https://learn.microsoft.com/en-us/ef/core/cli/powershell#drop-database) | Drops the database.
+[Get-Migration](https://learn.microsoft.com/en-us/ef/core/cli/powershell#get-migration) | Lists available migrations.
+[Optimize-DbContext](https://learn.microsoft.com/en-us/ef/core/cli/powershell#optimize-dbcontext) | Generates a compiled version of the model used by the `DbContext`.
+[Remove-Migration](https://learn.microsoft.com/en-us/ef/core/cli/powershell#remove-migration) | Removes the last migration snapshot.
+[Scaffold-DbContext](https://learn.microsoft.com/en-us/ef/core/cli/powershell#scaffold-dbcontext) | Generates a DbContext and entity type classes for a specified database. This is called reverse engineering.
+[Script-DbContext](https://learn.microsoft.com/en-us/ef/core/cli/powershell#script-dbcontext) | Generates a SQL script from the DbContext. Bypasses any migrations.
+[Script-Migration](https://learn.microsoft.com/en-us/ef/core/cli/powershell#script-migration) |  Generates a SQL script using all the migration snapshots.
+[Update-Database](https://learn.microsoft.com/en-us/ef/core/cli/powershell#update-database) | Updates the database schema based on the last migration snapshot.
+
+## Additional documentation
+
+- [Migrations](https://learn.microsoft.com/en-us/ef/core/managing-schemas/migrations/)
+- [Reverse Engineering](https://learn.microsoft.com/en-us/ef/core/managing-schemas/scaffolding/?tabs=dotnet-core-cli)
+- [Compiled models](https://learn.microsoft.com/en-us/ef/core/performance/advanced-performance-topics?tabs=with-di%2Cwith-constant#compiled-models)
+
+## Feedback
+
+If you encounter a bug or issues with this package,you can [open 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).