Update linux install instructions
Update linux install instructions

in apache2 version 2.4.7+ the root directory is now /var/www/html and NOT /var/www
inverse/emoncms,chaveiro/emoncms,emoncms/emoncms,emoncms/emoncms,thaipowertech/emoncms,emoncms/emoncms,thaipowertech/emoncms,emoncms/emoncms,inverse/emoncms,inverse/emoncms,jeremypoulter/emoncms,jeremypoulter/emoncms,jeremypoulter/emoncms,jeremypoulter/emoncms,emoncms/emoncms,thaipowertech/emoncms,chaveiro/emoncms,thaipowertech/emoncms,chaveiro/emoncms,inverse/emoncms,chaveiro/emoncms