etcdctl: Add dot at the end of sentences
@@ -1085,11 +1085,11 @@ echo ${transferee_id}
### DOWNGRADE \<subcommand\>
-Downgrade provides commands to downgrade cluster version
+Downgrade provides commands to downgrade cluster version.
### DOWNGRADE VALIDATE \<TARGET_VERSION\>
-DOWNGRADE VALIDATE validate downgrade capability before starting downgrade
+DOWNGRADE VALIDATE validate downgrade capability before starting downgrade.
#### Example
@@ -1104,7 +1104,7 @@ Error: etcdserver: invalid downgrade target version
### DOWNGRADE ENABLE \<TARGET_VERSION\>
-DOWNGRADE ENABLE starts a downgrade action to cluster
+DOWNGRADE ENABLE starts a downgrade action to cluster.
#### Example
@@ -1115,7 +1115,7 @@ Downgrade enable success, cluster version 3.6.0
### DOWNGRADE CANCEL \<TARGET_VERSION\>
-DOWNGRADE CANCEL cancels the ongoing downgrade action to cluster
+DOWNGRADE CANCEL cancels the ongoing downgrade action to cluster.
#### Example
