Documentation should emphasise use of optimised Maxima images

[aharjula]

Some users have had issues with very slow Maxima startup speeds in their pools and have reported that optimised (memory image) based solutions have fixed their problems. When we have time we should point this out in the documentation. Also tomcat versions and such might need to be updated.

Memory images should also offset any costs related to Meltdown related sys-call price increases. But that probably is not an issue.