Equals(Object) and GetHashCode() overrides look wrong

### Type of issue

Typo

### Description

In the definition of class Box in the code example, the override of Equals(Object) calls base.Equals(obj) which does not use the custom logic for equality defined in that class. It should call Equals(obj as Box) to use the custom logic. The overridden GetHashCode() should probably also be updated to use custom logic from class Box instead of calling the base class implementation.

### Page URL

https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.icollection-1?view=net-9.0#code-try-1

### Content source URL

https://github.com/dotnet/dotnet-api-docs/blob/main/xml/System.Collections.Generic/ICollection`1.xml

### Document Version Independent Id

d9a82967-6fd7-31b9-6fc9-377daa1a51d4

### Platform Id

9cb26e83-4075-c213-0708-b9ded52b04f6

### Article author

@dotnet-bot