Update prestation.cfg

Updated descriptions for system path names. Some path names are temporary (i.e. cleared/updated each time HeliPlot is run, these include seedpath and plotspath), others are unique to the server (i.e. seed/response paths for each station). The end-user needs to ensure that the server contains a path similar to that found on the aslres01 for network dataless files and frequency responses for each station (/APPS/metadata/SEED/, /APPS/metadata/RESPS/).