csgrep --help: mention forgotten --mode=evtstat

Author: kdudka

src/csgrep.cc

@@ -556,7 +556,7 @@ int main(int argc, char *argv[])
             ("quiet,q",                                         "do not report any parsing errors")
 
             ("mode",                po::value<string>(&mode)
-                                    ->default_value("grep"),    "grep, json, stat, grouped, files, filestat, or dig_key_events")
+                                    ->default_value("grep"),    "grep, json, evtstat, files, filestat, grouped, stat, or dig_key_events")
 
             ("help",                                            "print the usage of csgrep")
             ("version",                                         "print the version of csgrep");