[API] Generator: Add comment about stability to documentation

Author: picandocodigo

elasticsearch-api/utils/thor/generate_source.rb

@@ -235,6 +235,32 @@ def docs_helper(name, info)
         "# @option arguments [#{tipo}] :#{name} #{description} #{required} #{deprecated} #{options}\n"
       end
 
+      def stability_doc_helper(stability)
+        return if stability == 'stable'
+
+        if stability == 'experimental'
+          <<~MSG
+            # This functionality is Experimental and may be changed or removed
+            # completely in a future release. Elastic will take a best effort approach
+            # to fix any issues, but experimental features are not subject to the
+            # support SLA of official GA features.
+          MSG
+        elsif stability == 'beta'
+          <<~MSG
+            # This functionality is in Beta and is subject to change. The design and
+            # code is less mature than official GA features and is being provided
+            # as-is with no warranties. Beta features are not subject to the support
+            # SLA of official GA features.
+          MSG
+        else
+          <<~MSG
+            # This functionality is subject to potential breaking changes within a
+            # minor version, meaning that your referencing code may break when this
+            # library is upgraded.
+          MSG
+        end
+      end
+
       def generate_tests
         copy_file 'templates/test_helper.rb', @output.join('test').join('test_helper.rb')
 

elasticsearch-api/utils/thor/templates/_documentation_top.erb

@@ -3,6 +3,7 @@
 <%- else %>
   <%= '  '*(@namespace_depth+3) %># TODO: Description
 <%- end %>
+<%= stability_doc_helper(@spec['stability']) -%>
 <%= '  '*(@namespace_depth+3) %>#
 <%- unless @parts.nil? || @parts.empty? %><%# URL parts -%>
   <%- @parts.each do |name, info| -%>