Current behavior

In the angular documenation
https://angular.io/styleguide#!#04-10

It's writtent :
Do not provide services in shared modules. Services are usually singletons that are provided once for the entire application or in a particular feature module.

Expected behavior

Do should be used for positive phrases, Avoid for negative phrases.

The advice is really contradicting, especially given that services are used in the shared module given as example below this advice.

Depending on what you actually meant the phrase should either be changed to :

Avoid providing services in shared modules. Services are ...
or
Do provide services in shared modules. Services are ...