Remove reference to core HAL module in REST docs

Problem/Motivation

The REST module contains a reference to core HAL module and that is no longer in core.

Installing supporting modules
In order to use REST on a website, you need to install modules that provide serialization and authentication services. You can use the Core module HAL for serialization and HTTP Basic Authentication for authentication, or install a contributed or custom module.

Steps to reproduce

Proposed resolution

Change help text in rest.module to the following,

Installing supporting modules
In order to use REST on a website, you need to install modules that provide serialization and authentication services. You can use the Core module SERIALIZATION for serialization and HTTP Basic Authentication for authentication, or install a contributed or custom module.

Remaining tasks

Patch
review
commit

User interface changes

API changes

Data model changes

Release notes snippet