Split parser/serializer docs (#4690)

plugins/parsers/logfmt/README.md

@@ -0,0 +1,34 @@
+# Logfmt
+
+The `logfmt` data format parses data in [logfmt] format.
+
+[logfmt]: https://brandur.org/logfmt
+
+### Configuration
+
+```toml
+[[inputs.file]]
+  files = ["example"]
+
+  ## Data format to consume.
+  ## Each data format has its own unique set of configuration options, read
+  ## more about them here:
+  ##   https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
+  data_format = "logfmt"
+
+  ## Set the name of the created metric, if unset the name of the plugin will
+  ## be used.
+  metric_name = "logfmt"
+```
+
+### Metrics
+
+Each key/value pair in the line is added to a new metric as a field.  The type
+of the field is automatically determined based on the contents of the value.
+
+### Examples
+
+```
+- method=GET host=example.org ts=2018-07-24T19:43:40.275Z connect=4ms service=8ms status=200 bytes=1653
++ logfmt method="GET",host="example.org",ts="2018-07-24T19:43:40.275Z",connect="4ms",service="8ms",status=200i,bytes=1653i
+```