Split parser/serializer docs (#4690)

plugins/serializers/influx/README.md

@@ -0,0 +1,34 @@
+# Influx
+
+The `influx` data format outputs metrics into [InfluxDB Line Protocol][line
+protocol].  This is the recommended format unless another format is required
+for interoperability.
+
+### Configuration
+```toml
+[[outputs.file]]
+  ## Files to write to, "stdout" is a specially handled file.
+  files = ["stdout", "/tmp/metrics.out"]
+
+  ## Data format to output.
+  ## 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_OUTPUT.md
+  data_format = "influx"
+
+  ## Maximum line length in bytes.  Useful only for debugging.
+  influx_max_line_bytes = 0
+
+  ## When true, fields will be output in ascending lexical order.  Enabling
+  ## this option will result in decreased performance and is only recommended
+  ## when you need predictable ordering while debugging.
+  influx_sort_fields = false
+
+  ## When true, Telegraf will output unsigned integers as unsigned values,
+  ## i.e.: `42u`.  You will need a version of InfluxDB supporting unsigned
+  ## integer values.  Enabling this option will result in field type errors if
+  ## existing data has been written.
+  influx_uint_support = false
+```
+
+[line protocol]: https://docs.influxdata.com/influxdb/latest/write_protocols/line_protocol_tutorial/