Add edits for prometheus module docs (elastic#3520)

metricbeat/docs/fields.asciidoc

@@ -4708,7 +4708,7 @@ Time at which these statistics were last reset.
 == Prometheus Fields
 
 beta[]
-Prometheus Module
+Stats collected from Prometheus.
 
 
 
@@ -4721,14 +4721,14 @@ Prometheus Module
 [float]
 == stats Fields
 
-stats
+Stats about the Prometheus server.
 
 
 
 [float]
 == notifications Fields
 
-Notification stats
+Notification stats.
 
 
 
@@ -4737,31 +4737,31 @@ Notification stats
 
 type: long
 
-Current queue length
+Current queue length.
 
 
 [float]
 === prometheus.stats.notifications.dropped
 
 type: long
 
-Dropped queue events
+Number of dropped queue events.
 
 
 [float]
 === prometheus.stats.processes.open_fds
 
 type: long
 
-Open file descriptors gauge
+Number of open file descriptors.
 
 
 [float]
 === prometheus.stats.storage.chunks_to_persist
 
 type: long
 
-Gauge on chunks which are not persisted to disk yet
+Number of memory chunks that are not yet persisted to disk.
 
 
 [[exported-fields-redis]]

metricbeat/docs/modules/prometheus.asciidoc

@@ -3,12 +3,12 @@ This file is generated! See scripts/docs_collector.py
 ////
 
 [[metricbeat-module-prometheus]]
-== prometheus Module
+== Prometheus Module
 
 beta[]
 
-This is the prometheus Module.
-
+This module periodically fetches metrics from
+https://prometheus.io/docs/[Prometheus].
 
 
 [float]

metricbeat/module/prometheus/_meta/docs.asciidoc

@@ -1,6 +1,6 @@
-== prometheus Module
+== Prometheus Module
 
 beta[]
 
-This is the prometheus Module.
-
+This module periodically fetches metrics from
+https://prometheus.io/docs/[Prometheus].

metricbeat/module/prometheus/_meta/fields.yml

@@ -2,8 +2,8 @@
   title: "Prometheus"
   description: >
     beta[]
-
-    Prometheus Module
+    
+    Stats collected from Prometheus.
   short_config: false
   fields:
     - name: prometheus

metricbeat/module/prometheus/collector/_meta/docs.asciidoc

@@ -1,5 +1,7 @@
-=== prometheus collector MetricSet
+=== Prometheus Collector Metricset
 
-This is the collector metricset of the module prometheus. It allows to fetch data from https://prometheus.io/docs/instrumenting/exporters/[prometheus exporters].
+The Prometheus `collector` metricset fetches data from https://prometheus.io/docs/instrumenting/exporters/[prometheus exporters].
 
-All events with the same labels are grouped together as one event.
+All events with the same labels are grouped together as one event. The fields
+exported by this metricset vary depending on the Prometheus exporter that you're
+using.

metricbeat/module/prometheus/stats/_meta/docs.asciidoc

@@ -1,3 +1,4 @@
-=== prometheus stats MetricSet
+=== Prometheus Stats Metricset
 
-This is the stats metricset of the module prometheus.
+The Prometheus `stats` metricset collects statistics about the Prometheus
+server.

metricbeat/module/prometheus/stats/_meta/fields.yml

@@ -1,26 +1,26 @@
 - name: stats
   type: group
   description: >
-    stats
+    Stats about the Prometheus server.
   fields:
     - name: notifications
       type: group
       description: >
-        Notification stats
+        Notification stats.
       fields:
         - name: queue_length
           type: long
           description: >
-            Current queue length
+            Current queue length.
         - name: dropped
           type: long
           description: >
-            Dropped queue events
+            Number of dropped queue events.
     - name: processes.open_fds
       type: long
       description: >
-        Open file descriptors gauge
+        Number of open file descriptors.
     - name: storage.chunks_to_persist
       type: long
       description: >
-        Gauge on chunks which are not persisted to disk yet
+        Number of memory chunks that are not yet persisted to disk.