Inconsistent argument naming in salt.modules.slack_notify.call_hook

[Daniel-Lecoq]

Description
To use the function call_hook in the module slack_notify you need to do the following

salt '*' slack.call_hook message='Hello, from SaltStack' identifier='T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX'

However, if you want to put the identifier in a configuration file eg. /etc/salt/minion.d/slack.conf the following wont work:

slack:
  identifier: T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX

sudo salt 'minion-1' slack.call_hook message='Hello, from SaltStack'
minion-1:
    ERROR executing 'slack.call_hook': No Slack WebHook url found

you need to write

slack:
  hook: T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX

This is not documented anywhere (I had to go look at the code for the module) and the error message isn't very helpful since it doesn't tell you what argument name it's looking for.

Suggested Fix
Simple fix: Update the documentation

Moderate fix: Update the documentation, error message and match the expected name in the configuration file with the expected name of the argument on the commandline (hook != identifier)

Outside scope: There are multiple returners and modules for Slack. If they could be synchronised so that we only need one configuration file for Slack that works across returners and modules that would simplify setup quite a bit.

Type of documentation
Salt modules

Location or format of documentation
https://docs.saltstack.com/en/3001/ref/modules/all/salt.modules.slack_notify.html

Additional context

    Salt Version:
               Salt: 3001.1

    Dependency Versions:
               cffi: Not Installed
           cherrypy: Not Installed
           dateutil: Not Installed
          docker-py: Not Installed
              gitdb: Not Installed
          gitpython: Not Installed
             Jinja2: 2.8.1
            libgit2: Not Installed
           M2Crypto: 0.33.0
               Mako: Not Installed
       msgpack-pure: Not Installed
     msgpack-python: 0.6.2
       mysql-python: Not Installed
          pycparser: Not Installed
           pycrypto: Not Installed
       pycryptodome: Not Installed
             pygit2: Not Installed
             Python: 3.6.8 (default, May  6 2020, 12:04:35)
       python-gnupg: Not Installed
             PyYAML: 3.11
              PyZMQ: 17.0.0
              smmap: Not Installed
            timelib: Not Installed
            Tornado: 4.5.3
                ZMQ: 4.1.4

    System Versions:
               dist: rhel 7.8 Maipo
             locale: UTF-8
            machine: x86_64
            release: 3.10.0-1127.19.1.el7.x86_64
             system: Linux
            version: Red Hat Enterprise Linux Server 7.8 Maipo

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[sagetherage]

updating this as a docs missing reference giving it a higher severity as the docs missing needs attention