Update AIO references

https://access.redhat.com/documentation/en-us/red_hat_amq/2020.q4/html-single/getting_started_with_amq_broker/index#broker-instances-getting-started

says AIO is best performance, but has requirements:

• Linux Kernel version 2.6 or later - doesn't make sense anymore - remove
• Supported file system - as documented in 'Supported Configs' [1] should point to `Supported network file systems`

[1] https://access.redhat.com/articles/2791941