Don't use absolute paths in the example file

Author: jedisct1

dnscrypt-proxy/example-dnscrypt-proxy.toml

@@ -756,7 +756,7 @@ format = 'tsv'
   #  [sources.dnscry-pt-resolvers]
   #    urls = ["https://www.dnscry.pt/resolvers.md"]
   #    minisign_key = "RWQM31Nwkqh01x88SvrBL8djp1NH56Rb4mKLHz16K7qsXgEomnDv6ziQ"
-  #    cache_file = "/var/cache/dnscrypt-proxy/dnscry.pt-resolvers.md"
+  #    cache_file = "dnscry.pt-resolvers.md"
   #    refresh_delay = 72
   #    prefix = "dnscry.pt-"