[DOCS] state_top_saltenv documention is inaccurate in regard to when it applies

Description

This option has no default value. Set it to an environment name to ensure that only the top file from that environment is considered during a highstate.

The docs here are wrong. The "ensure that only the top file from that environment is considered" is only applicable if saltenv is not specified by the minion.

https://github.com/saltstack/salt/blob/29b6843268e9877c28bd283b0aa9d77e4bae948d/salt/state.py#L3892-L3920

Suggested Fix
Update the docs to indicate that it will only apply if the minion does not have a saltenv configured. I believe this setting is more accurately described as a saltenv fallback, as it behaves very similar to if saltenv was configured.

Location or format of documentation
https://docs.saltproject.io/en/latest/ref/configuration/master.html#state-top-saltenv
https://docs.saltproject.io/en/latest/ref/configuration/minion.html#state-top-saltenv

Additional context
I actually like the way the option currently works. I do /not/ believe it should be changed.

Read the state.py lines linked in the issue to confirm when state_top_saltenv applies. Update the state_top_saltenv sections in the master and minion configuration documentation to describe it as a saltenv fallback when no minion saltenv is configured. Done means both pages accurately document the current behavior without changing the option.