Acpid: Better document the events/anything file

[0x5c]

In the Power Management section, acpid and elogind are both mentioned, along with the incompatibility between them. However, the only documented "solution" is to completely disable acpid (which breaks things like acpi_listen) or completely remove acpi handling from elogind (which break proper sleep/etc handling in DEs which use it).

In reality, commenting out or removing /etc/acpi/events/anything is enough to disable the handlers on the acpid side. This is a 3rd option, and the only one of these that works when both elogind's handling is needed by a DE and the acpid socket (or custom handlers) are required. Perhaps this could be mentioned as a solution when disabling acpid or elogin's handlers is not possible.