Fix spelling and clarify docs (influxdata#8164)

plugins/processors/topk/README.md

@@ -1,16 +1,18 @@
 # TopK Processor Plugin
 
-The TopK processor plugin is a filter designed to get the top series over a period of time. It can be tweaked to do its top k computation over a period of time, so spikes can be smoothed out.
+The TopK processor plugin is a filter designed to get the top series over a period of time. It can be tweaked to calculate the top metrics via different aggregation functions.
 
 This processor goes through these steps when processing a batch of metrics:
 
-  1. Groups metrics in buckets using their tags and name as key
-  2. Aggregates each of the selected fields for each bucket by the selected aggregation function (sum, mean, etc)
-  3. Orders the buckets by one of the generated aggregations, returns all metrics in the top `K` buckets, then reorders the buckets by the next of the generated aggregations, returns all metrics in the top `K` buckets, etc, etc, etc, until it runs out of fields.
+  1. Groups measurements in buckets based on their tags and name
+  2. Every N seconds, for each bucket, for each selected field: aggregate all the measurements using a given aggregation function (min, sum, mean, etc) and the field.
+  3. For each computed aggregation: order the buckets by the aggregation, then returns all measurements in the top `K` buckets
 
-The plugin makes sure not to duplicate metrics
-
-Note that depending on the amount of metrics on each computed bucket, more than `K` metrics may be returned
+Notes:
+  * The deduplicates metrics
+  * The name of the measurement is always used when grouping it
+  * Depending on the amount of metrics on each  bucket, more than `K` series may be returned
+  * If a measurement does not have one of the selected fields, it is dropped from the aggregation
 
 ### Configuration:
 
@@ -19,46 +21,40 @@ Note that depending on the amount of metrics on each computed bucket, more than
   ## How many seconds between aggregations
   # period = 10
 
-  ## How many top metrics to return
+  ## How many top buckets to return
   # k = 10
 
-  ## Over which tags should the aggregation be done. Globs can be specified, in
-  ## which case any tag matching the glob will aggregated over. If set to an
-  ## empty list is no aggregation over tags is done
+  ## Based on which tags should the buckets be computed. Globs can be specified.
+  ## If set to an empty list tags are not considered when creating the buckets
   # group_by = ['*']
 
-  ## Over which fields are the top k are calculated
+  ## Over which fields is the aggregation done
   # fields = ["value"]
 
-  ## What aggregation to use. Options: sum, mean, min, max
+  ## What aggregation function to use. Options: sum, mean, min, max
   # aggregation = "mean"
 
-  ## Instead of the top k largest metrics, return the bottom k lowest metrics
+  ## Instead of the top k buckets, return the bottom k buckets
   # bottomk = false
 
-  ## The plugin assigns each metric a GroupBy tag generated from its name and
-  ## tags. If this setting is different than "" the plugin will add a
-  ## tag (which name will be the value of this setting) to each metric with
-  ## the value of the calculated GroupBy tag. Useful for debugging
+  ## This setting provides a way to know wich metrics where group together.
+  ## Add a tag (which name will be the value of this setting) to each metric.
+  ## The value will be the tags used to pick its bucket.
   # add_groupby_tag = ""
 
-  ## These settings provide a way to know the position of each metric in
-  ## the top k. The 'add_rank_field' setting allows to specify for which
-  ## fields the position is required. If the list is non empty, then a field
-  ## will be added to each and every metric for each string present in this
-  ## setting. This field will contain the ranking of the group that
-  ## the metric belonged to when aggregated over that field.
+  ## This setting provides a way to know the position of each metric's bucket in the top k
+  ## If the list is non empty, a field will be added to each and every metric
+  ## for each string present in this setting. This field will contain the ranking
+  ## of the bucket that the metric belonged to when aggregated over that field.
   ## The name of the field will be set to the name of the aggregation field,
   ## suffixed with the string '_topk_rank'
   # add_rank_fields = []
 
   ## These settings provide a way to know what values the plugin is generating
-  ## when aggregating metrics. The 'add_aggregate_field' setting allows to
-  ## specify for which fields the final aggregation value is required. If the
-  ## list is non empty, then a field will be added to each every metric for
-  ## each field present in this setting. This field will contain
-  ## the computed aggregation for the group that the metric belonged to when
-  ## aggregated over that field.
+  ## when aggregating metrics. If the list is non empty, then a field will be
+  ## added to each every metric for each field present in this setting.
+  ## This field will contain the computed aggregation for the bucket that the
+  ## metric belonged to when aggregated over that field.
   ## The name of the field will be set to the name of the aggregation field,
   ## suffixed with the string '_topk_aggregate'
   # add_aggregate_fields = []