docs: added undocumented step api parameter format
@@ -132,7 +132,7 @@ URL query parameters:
- `query=<string>`: Prometheus expression query string.
- `start=<rfc3339 | unix_timestamp>`: Start timestamp.
- `end=<rfc3339 | unix_timestamp>`: End timestamp.
-- `step=<duration>`: Query resolution step width.
+- `step=<duration | float>`: Query resolution step width in `duration` format or float number of seconds.
- `timeout=<duration>`: Evaluation timeout. Optional. Defaults to and
is capped by the value of the `-query.timeout` flag.
