Update and add missing descriptions to ETCD module (elastic#10592)

(cherry picked from commit da2c258)

# Conflicts:
#	metricbeat/docs/fields.asciidoc
#	metricbeat/module/etcd/fields.go

metricbeat/docs/fields.asciidoc

@@ -5233,13 +5233,17 @@ The number of failed and successful Raft RPC requests.
 --
 type: integer
 
+successful Raft RPC requests
+
 --
 
 *`etcd.leader.followers.counts.followers.counts.fail`*::
 +
 --
 type: integer
 
+failed Raft RPC requests
+
 --
 
 [float]
@@ -5289,6 +5293,8 @@ type: scaled_float
 --
 type: keyword
 
+ID of actual leader
+
 --
 
 [float]
@@ -5323,14 +5329,17 @@ id of the current leader member
 --
 type: keyword
 
+the time when this node was started
+
+
 --
 
 *`etcd.self.leaderinfo.uptime`*::
 +
 --
 type: keyword
 
-id of the current leader member
+amount of time the leader has been leader
 
 
 --

metricbeat/module/etcd/leader/_meta/fields.yml

@@ -11,8 +11,10 @@
       fields:
         - name: followers.counts.success
           type: integer
+          description: successful Raft RPC requests
         - name: followers.counts.fail
           type: integer
+          description: failed Raft RPC requests
 
 
     - name: followers.latency
@@ -32,4 +34,5 @@
           type: scaled_float
     - name: leader
       type: keyword
+      description: ID of actual leader
 

metricbeat/module/etcd/self/_meta/fields.yml

@@ -15,10 +15,12 @@
         id of the current leader member
     - name: leaderinfo.starttime
       type: keyword
+      description: >
+        the time when this node was started
     - name: leaderinfo.uptime
       type: keyword
       description: >
-        id of the current leader member
+        amount of time the leader has been leader
 
     - name: name
       type: keyword