Duplicated delegate section

### Type of issue

Typo

### Description

This section is duplicated by a similar section in the programming guide. They should be combined.

In addition:

- The terms "named delegate", "anonymous delegate", "lambda expression", and "method group" all need to be clearly defined. They aren't currently, and that leads to some confusion.
- The nuance around multi-cast delegates needs more clarification.

### Page URL

https://learn.microsoft.com/en-us/dotnet/csharp/delegates-overview

### Content source URL

https://github.com/dotnet/docs/blob/main/docs/csharp/delegates-overview.md

### Document Version Independent Id

b2b5c0f5-35d8-80da-2740-a099b75bbed0

### Article author

@BillWagner

### Metadata

* ID: 134d3592-25e8-0650-b502-fa66ee0ed3c2
* Service: **dotnet-csharp**
* Sub-service: **fundamentals**