Some of the new cloud sys log collection hooks are missing support for the creds file use case and documentation

[Dannyb48]

Describe the bug

During my POC testing of hooks in Carbon, I was having a hard time using the new boot log collection hooks using the example from docs/workspaces/openstack-simple. Specifically it fails with

2020-01-21 16:38:20,865 INFO [carbon.provisioners.ext.linchpin.linchpin_wrapper_plugin.write:73] fatal: [10.0.152.177 -> localhost]: FAILED! => {
    "changed": true, 
    "cmd": [
        "openstack", 
        "console", 
        "log", 
        "show", 
        "0dc1f16c-5b0d-40ff-82b6-125cfb4ef4a0"
    ], 
    "delta": "0:00:00.888154", 
    "end": "2020-01-21 16:38:20.845032", 
    "invocation": {
        "module_args": {
            "_raw_params": "openstack console log show 0dc1f16c-5b0d-40ff-82b6-125cfb4ef4a0", 
            "_uses_shell": false, 
            "argv": null, 
            "chdir": null, 
            "creates": null, 
            "executable": null, 
            "removes": null, 
            "stdin": null, 
            "stdin_add_newline": true, 
            "strip_empty_ends": true, 
            "warn": true
        }
    }, 
    "msg": "non-zero return code", 
    "rc": 1, 
    "start": "2020-01-21 16:38:19.956878", 
    "stderr": "Missing value auth-url required for auth plugin password", 
    "stderr_lines": [
        "Missing value auth-url required for auth plugin password"
    ], 
    "stdout": "", 
    "stdout_lines": []
}

Based on the openstack openstack cli docs openstack command will either use any OS_* variables exported or any cloud.yml files in the following directories

Current Directory
~/.config/openstack
/etc/openstack

Once it finds the cloud yaml you still need to specify which cloud profile to use either using the OS_CLOUD variable or CLI option --os-cloud=<profile name>

In my testing I'm using the the clouds.yml and passing it to linchpin using the credentials key in the pinfile. The current implementation of the os_server_boot_log won't work unles the OS_* variables are exported.

I think right now the only one that can probably work with the credentials file option is the Azure one. The OS, EC2, and OCP ones probably won't work.

Plus I think user documentation is missing, I couldn't find anything on the new hooks or at the very least what are the specific vars/params that need to be specified in the cfgs or layout section of the PinFile/Topology that the built in hook requires to function.

To Reproduce
Steps to reproduce the behavior:

1. pip install linchpin
2. cd `docs/workspace
3. Scroll down to '....'
4. See error