Add what's new in 7E page

README.md

@@ -60,6 +60,7 @@ The appendix and color figures are available to download as PDFs:
 Corrections for typos and other mistakes and improvements like refactoring code. Useful links to other related material. 
 - [Book Links](book-links.md)
 - [Improvements & Errata - list of corrections](docs/errata)
+- [What's New in the 7th Edition](docs/whats-new.md)
 - [Seventh edition's support for .NET 8](docs/dotnet8.md)
 
 ## Microsoft Certifications

docs/whats-new.md

@@ -0,0 +1,79 @@
+**What's New in the 7th Edition**
+
+There are hundreds of minor fixes and improvements throughout the 7th edition; too many to list individually. All errata and improvements listed [here](https://github.com/markjprice/cs10dotnet6/blob/main/docs/errata/README.md) have been made to the 7th edition. 
+
+The main new sections in C# 11 and .NET 7, 7th edition compared to C# 10 and .NET 6 6th edition are shown below.
+
+# Chapter 1
+
+- Understanding .NET support: explains that *Current* support is now renamed *Standard Term Support (STS)*.
+
+# Chapter 2
+
+- Raw string literals and Raw interpolated string literals: new C# 11 features.
+
+# Chapter 3
+
+- Storing multiple values in an array: not a new feature but previous editions didn't really cover arrays.
+- List pattern matching with arrays: a new C# 11 feature.
+
+# Chapter 4
+
+- Understanding top-level programs and functions: I explain in detail how top-level programs work with separate files for `partial Program` class since I use that technique throughout the book.
+- Most of the function examples have been improved based on reader feedback, for example, going beyond supported ranges to see when exceptions and overflows occur.
+- A brief aside about the correct usage of the terms *arguments* and *parameters*.
+- Hot reloading during development.
+- Logging information about your source code.
+
+# Chapter 5
+
+- Avoiding a namespace conflict with a using alias, and Renaming a type with a using alias. Not new but useful for readers to know.
+- Requiring properties to be set during instantiation: the new C# 11 `required` keyword.
+
+# Chapter 6
+
+- Checking for `null` in method parameters: explains the story behind `!!` in C# 11.
+- Treating warnings as errors: added for good practice.
+- Understanding warning waves.
+
+# Chapter 7
+
+- Viewing source links with Visual Studio 2022: explain differences between viewing source links and decompiling, with `Enumerable.Count` method as an example which then helps to understand later why `Count()` can be inefficient.
+
+# Chapter 8
+
+- Activating regular expression syntax coloring: the new `[StringSyntax]` attribute introduced in .NET 7.
+- Improving regular expression performance with source generators.
+
+# Chapter 9
+
+- Working with Tar archives. New in .NET 7.
+
+# Chapter 10
+
+- Customizing the reverse engineering templates: I just mention that this is possible because it's interesting but too advanced for this book.
+- More efficient updates and deletes. Uses new methods in EF Core 7.
+
+# Chapter 11
+
+- Sorting by the item itself. Uses new methods in .NET 7.
+- Be careful with Count! A section about the `Count()` method implementation and how it can be tricky to work with efficiently.
+- Paging with LINQ. A new section for the book but not a new LINQ feature. Just helpful to cover before getting into web development.
+
+# Chapter 13
+
+- Enabling request decompression support.
+- Enabling HTTP/3 support.
+
+# Chapter 14
+
+- Using output caching. Output caching was added in ASP.NET Core 7.
+
+# Chapter 15
+
+- Support for logging additional request headers in W3CLogger.
+- Enabling HTTP/3 support for HttpClient.
+
+# Chapter 16
+
+- Enabling location change event handling.