Documentation Revamp

Co-authored-by: jbdoumenjou <jb.doumenjou@gmail.com>

docs/content/observability/logs.md

@@ -0,0 +1,50 @@
+# Logs
+
+Reading What's Happening
+{: .subtitle }
+
+By default, logs are written to stdout, in text format.
+
+## Configuration Example
+
+??? example "Writing Logs in a File"
+
+    ```toml
+    [log]
+    filePath = "/path/to/traefik.log"
+    ```
+
+??? example "Writing Logs in a File, in JSON"
+
+    ```toml
+    [log]
+    filePath = "/path/to/log-file.log"
+    format   = "json"
+    ```
+
+## Configuration Options
+
+### General
+
+Traefik logs concern everything that happens to Traefik itself (startup, configuration, events, shutdown, and so on).
+
+#### filePath
+
+By default, the logs are written to the standard output.
+You can configure a file path instead using the `filePath` option.
+
+#### format
+
+By default, the logs use a text format (`common`), but you can also ask for the `json` format in the `format` option.   
+
+#### logLevel
+
+By default, the `logLevel` is set to `error`, but you can choose amongst `debug`, `panic`, `fatal`, `error`, `warn`, and `info`. 
+
+## Log Rotation
+
+Traefik will close and reopen its log files, assuming they're configured, on receipt of a USR1 signal.
+This allows the logs to be rotated and processed by an external program, such as `logrotate`.
+
+!!! note
+    This does not work on Windows due to the lack of USR signals.