give a warning in documentation if syslog-logs parser is missing
!!! info
Please ensure that you have working env or setup test environment before writing your parser.
+!!! warning "Parser dependency"
+
+The crowdsecurity/syslog-logs parsers is needed by the core parsing
+engine. Deletion or modification of this could result of {{crowdsec.name}}
+being unable to parse logs, so this should be done very carefully.
+
> In the current example, we'll write a parser for the logs produced by `iptables` (netfilter) with the `-j LOG` target.
> This document aims at detailing the process of writing and testing new parsers.
