Improve AppSizeMetricsHelper documentation

Author: AliSoftware

lib/fastlane/plugin/wpmreleasetoolkit/helper/app_size_metrics_helper.rb

@@ -4,6 +4,11 @@
 
 module Fastlane
   module WPMRT
+    # A helper class to build an App Size Metrics payload and send it to a server (or write it to disk)
+    #
+    # The payload generated (and sent) by this helper conforms to the API for grouped metrics described in
+    # https://github.com/Automattic/apps-metrics
+    #
     class AppSizeMetricsHelper
       # @param [Hash] group_meta Metadata common to all the metrics. Can be any arbitrary set of key/value pairs.
       #
@@ -12,9 +17,9 @@ def initialize(group_meta = {})
         @metrics = []
       end
 
-      # Sets the metadata for the whole group of metrics in that payload
+      # Sets the metadata common to the whole group of metrics in the payload being built by this helper instance
       #
-      # @param [Hash] hash The metadata common to all the metrics to set on the whole payload. Can be any arbitrary set of key/value pairs
+      # @param [Hash] hash The metadata common to all the metrics of the payload built by that helper instance. Can be any arbitrary set of key/value pairs
       #
       def meta=(hash)
         @meta = (hash.compact || {}).map { |key, value| { name: key.to_s, value: value } }