Document new requirement for trait methods to be in scope in order to call them

[Savio-Sou]

Document:

• feat: require trait function calls (Foo::bar()) to have the trait in scope (imported) #6882
• feat!: require trait method calls (foo.bar()) to have the trait in scope (imported) #6895
• feat!: require trait primitive functions/calls to have their trait in scope #6900
• feat!: require trait primitive functions/calls to have their trait in scope #6901
• fix: require generic trait impls to be in scope to call them #6913