[DOCS] Salt Master Cluster Tutorial - Cache Directory

[clayoster]

Description
The suggested setting for moving the master cache to the shared filesystem appears to be incorrect. I have tried using cache_dir but nothing was written to my shared filesystem location. Errors are also generated about not being able to find jobs initiated by other masters and the path in the error indicates the default master cache path is still being used.

2024-03-23 10:12:58,395 [salt.master      :2093][ERROR   ][160450] Error in function _return:
Traceback (most recent call last):
  File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/returners/local_cache.py", line 309, in get_load
    with salt.utils.files.fopen(minions_path, "rb") as rfh:
  File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/utils/files.py", line 393, in fopen
    f_handle = open(*args, **kwargs)  # pylint: disable=resource-leakage
FileNotFoundError: [Errno 2] No such file or directory: '/var/cache/salt/master/jobs/d1/a5bd1ec0b4d790c092cd9d243e6d78c0e5f716e9a76968e2c4871e67d59761/.minions.p'

Using the cachedir setting instead causes master cache data to be written to my shared filesystem as expected and the error shown above was no longer seen.

Suggested Fix
Change cache_dir to cachedir in the Master Cluster tutorial.

Type of documentation
Tutorial

Location or format of documentation
https://docs.saltproject.io/en/master/topics/tutorials/master-cluster.html