docs: configuration example

The supplied example configuration is quite involved, probably to showcase all existing config directives, but it's probably not immediately applicable in a simple setup arranged for a proof-of-concept. I recommend to move the list of all config keys in a separate doc and provide a simpler example (or a few of them of increasing complexity). Maybe starting with:

writer_id = "mdt-dout-collector-01";
client_id = "mdt-dialout-collector";

iface = "eth0";

ipv4_socket_cisco = "0.0.0.0:10007";
ipv4_socket_huawei = "0.0.0.0:10008";
ipv4_socket_juniper = "0.0.0.0:10009";

replies_cisco = "10";
replies_juniper = "100";
replies_huawei = "1000";

cisco_workers = "1";
juniper_workers = "1";
huawei_workers = "1";

console_log = "true";
spdlog_level = "debug";
log_level = "0";

bootstrap_servers = "localhost:9093";
topic = "json.topic";
security_protocol = "plaintext";
enable_idempotence = "true";

network-analytics / mdt-dialout-collector

docs: configuration example #19