show service descriptions in each client document (#2544)

* show service descriptions in each client document

* better handle the formated string where {} could be escaped

doc-src/templates/api-versions/model_documentor.rb

@@ -1,6 +1,17 @@
 require 'ostruct'
 
 module Documentor
+  def service_overview(rules)
+    docs = documentation(rules)
+    docs = docs || '';
+    docs = docs.gsub(/<fullname>.+?<\/fullname>/, '')
+    docs = docs.gsub(/(.*?)\{(\S*?)\}/, '\1[\2]') ## replace {} in format string with []
+    if docs && (docs.include? 'runtime aspects of your deployed APIs')
+      puts docs
+    end
+    docs == '' ? nil : docs
+  end
+
   def documentation(rules)
     docs = rules['documentation'] || ''
     docs = docs.gsub(/<!--.*?-->/m, '')
@@ -37,12 +48,25 @@ class ModelDocumentor
 
   def initialize(klass, api)
     api_version = api['metadata']['apiVersion']
+    service_desc = service_overview(api)
     @lines = []
     @lines << ''
     @lines << <<-DOCS.strip
 Constructs a service interface object. Each API operation is exposed as a
 function on service.
+DOCS
+
+    if service_desc
+      @lines << <<-DOCS.strip
 
+### Service Description
+      
+#{service_desc}
+
+DOCS
+    end
+
+    @lines << <<-DOCS.strip
 ### Sending a Request Using #{klass}
 
 ```javascript