Merge branch 'mr/exsyslogger-doc-and-format' into 'develop'

Adds a couple examples to docs/config.md for ExSyslogger and removes duplicate timestamps from default format.

See merge request !784

config/config.exs

@@ -115,7 +115,7 @@ config :logger, :console,
 config :logger, :ex_syslogger,
   level: :debug,
   ident: "Pleroma",
-  format: "$date $time $metadata[$level] $message",
+  format: "$metadata[$level] $message",
   metadata: [:request_id]
 
 config :mime, :types, %{

docs/config.md

@@ -100,6 +100,26 @@ config :pleroma, Pleroma.Mailer,
 
 ## :logger
 * `backends`: `:console` is used to send logs to stdout, `{ExSyslogger, :ex_syslogger}` to log to syslog
+
+An example to enable ONLY ExSyslogger (f/ex in ``prod.secret.exs``) with info and debug suppressed:
+```
+config :logger, 
+  backends: [{ExSyslogger, :ex_syslogger}]
+
+config :logger, :ex_syslogger,
+  level: :warn
+```
+
+Another example, keeping console output and adding the pid to syslog output:
+```
+config :logger,
+  backends: [:console, {ExSyslogger, :ex_syslogger}]
+
+config :logger, :ex_syslogger,
+  level: :warn,
+  option: [:pid, :ndelay]
+```
+
 See: [logger’s documentation](https://hexdocs.pm/logger/Logger.html) and [ex_syslogger’s documentation](https://hexdocs.pm/ex_syslogger/)