Store metadata next to plugins code

[traut]

Background

The plugins and the data sources / content providers often require additional instructions and examples of the usage. At the moment this information is not stored anywhere.

Design

Store the metadata for the plugin/data sources/content providers next to the source code in a structured way so it can be used with the docgen tool to generate the documentation.

Plugin metadata

• description - (required) a string value. a Markdown text that describes the plugin

Data sources metadata

• description - (required) a string value
  • a Markdown text that provides a general description and explains configuration/execution attributes
• tags - a list of strings
• json_schema - a JSON blob that contains a JSON schema value for the returned data
  • loaded from output.json file stored next to the source code

Content provider metadata

• description - (required) a string value
  • a Markdown text that provides a general description and explains configuration/execution attributes
• tags - a list of strings

Additions

docgen should generate README.md per plugin file using the metadata form source / providers (description / tags / etc fields) and place it in the plugin's source folder