docs: update telegraf configuration.md (influxdata#3300)

* docs: update telegraf configuration.md

* add note about rate limits

content/telegraf/v1.20/administration/configuration.md

@@ -87,7 +87,7 @@ The environment variables above add the following configuration settings to Tele
 
 ```
 
-# Global tags
+## Global tags
 
 Global tags can be specified in the `[global_tags]` section of the config file
 in `key="value"` format. All metrics being gathered on this host will be tagged
@@ -126,16 +126,37 @@ be used for service inputs, such as `logparser` and `statsd`. Valid values are
 * **logfile**: Specify the log file name. The empty string means to log to `stderr`.
 * **debug**: Run Telegraf in debug mode.
 * **quiet**: Run Telegraf in quiet mode (error messages only).
+* **logtarget**: Control the destination for logs. Can be one of "file", 
+"stderr" or, on Windows, "eventlog".  When set to "file", the output file is
+determined by the "logfile" setting.
+* **logfile**: Name the file to be logged to when using the "file" logtarget.  If set 
+to the empty then logs are written to stderr.
+* **logfile_rotation_interval**: Rotates logfile after the time interval specified.  When 
+set to 0 no time based rotation is performed.
+* **logfile_rotation_max_size**: Rotates logfile when it becomes larger than the specified 
+size. When set to 0 no size based rotation is performed.
+* **logfile_rotation_max_archives**: Maximum number of rotated archives to keep, any 
+older logs are deleted.  If set to -1, no archives are removed.
+* **log_with_timezone**: Set a timezone to use when logging or type 'local' for local time. Example: 'America/Chicago'.
+  [See this page for options/formats.](https://socketloop.com/tutorials/golang-display-list-of-timezones-with-gmt)
 * **hostname**: Override default hostname, if empty use `os.Hostname()`.
 * **omit_hostname**: If true, do no set the `host` tag in the Telegraf agent.
+
 
 ## Input configuration
 
 The following config parameters are available for all inputs:
 
+* **alias**: Name an instance of a plugin.
 * **interval**: How often to gather this metric. Normal plugins use a single
 global interval, but if one particular input should be run less or more often,
-you can configure that here.
+you can configure that here. `interval` can be increased to reduce data-in rate limits. 
+* **precision**: Overrides the `precision` setting of the agent. Collected 
+metrics are rounded to the precision specified as an `interval`. When this value is 
+set on a service input (ex: `statsd`), multiple events occuring at the same 
+timestamp may be merged by the output database.
+* **collection_jitter**: Overrides the `collection_jitter` setting of the agent.  
+Collection jitter is used to jitter the collection by a random `interval`
 * **name_override**: Override the base name of the measurement.
 (Default is the name of the input).
 * **name_prefix**: Specifies a prefix to attach to the measurement name.
@@ -144,19 +165,36 @@ you can configure that here.
 
 ## Output configuration
 
-There are no generic configuration options available for all outputs.
+* **alias**: Name an instance of a plugin.
+* **flush_interval**: Maximum time between flushes. Use this setting to
+  override the agent `flush_interval` on a per plugin basis.
+* **flush_jitter**: Amount of time to jitter the flush interval. Use this
+  setting to override the agent `flush_jitter` on a per plugin basis.
+* **metric_batch_size**: Maximum number of metrics to send at once. Use
+  this setting to override the agent `metric_batch_size` on a per plugin basis.
+* **metric_buffer_limit**: Maximum number of unsent metrics to buffer.
+  Use this setting to override the agent `metric_buffer_limit` on a per plugin basis.
+* **name_override**: Override the base name of the measurement.
+(Default is the name of the output).
+* **name_prefix**: Specifies a prefix to attach to the measurement name.
+* **name_suffix**: Specifies a suffix to attach to the measurement name.
 
 ## Aggregator configuration
 
 The following config parameters are available for all aggregators:
 
+* **alias**: Name an instance of a plugin.
 * **period**: The period on which to flush & clear each aggregator. All metrics
 that are sent with timestamps outside of this period will be ignored by the
 aggregator.
 * **delay**: The delay before each aggregator is flushed. This is to control
 how long for aggregators to wait before receiving metrics from input plugins,
 in the case that aggregators are flushing and inputs are gathering on the
 same interval.
+* **grace**: The duration the metrics will still be aggregated by the plugin
+even though they're outside of the aggregation period. This setting is needed 
+in a situation when the agent is expected to receive late metrics and can 
+be rolled into next aggregation period.
 * **drop_original**: If true, the original metric will be dropped by the
 aggregator and will not get sent to the output plugins.
 * **name_override**: Override the base name of the measurement.
@@ -169,10 +207,15 @@ aggregator and will not get sent to the output plugins.
 
 The following config parameters are available for all processors:
 
+* **alias**: Name an instance of a plugin.
 * **order**: This is the order in which processors are executed. If this
 is not specified, then processor execution order will be random.
 
-#### Measurement filtering
+The [metric filtering][] parameters can be used to limit what metrics are
+handled by the processor.  Excluded metrics are passed downstream to the next
+processor.
+
+## Metric filtering
 
 Filters can be configured per input, output, processor, or aggregator,
 see below for examples.
@@ -212,6 +255,8 @@ must be defined at the _end_ of the plugin definition, otherwise subsequent
 plugin config options will be interpreted as part of the tagpass/tagdrop
 tables.
 
+## Examples
+
 #### Input configuration examples
 
 This is a full working config that will output CPU data to an InfluxDB instance