servers.cgi was the old (pre 2.0) frontend for displaying (and collecting) server information in MRTG. This functionality was merged into routers.cgi from v2.0 and so servers.cgi has been dropped.
You can enable the support with 'servers = yes' in the [routers.cgi] section of the routers2.conf file, and adding the [servers.cgi] section with the necessary definitions. However, it is better to use normal MRTG data collection via SNMP or mrtg-nrpe to collect and display data using the normal way.
UNIX Systems, ITSS, University of Auckland, NZ
Woe unto them that rise up early in the morning... -- Isaiah 5:11