ECS 1.0.1

Added

• Add generated source code for Go. #249
• Translate the documentation from README.md, to the main website. #266, #334, #400, #430, #435
• New generator that supports reusable fields, for files based on ECS.
  It generates schema.csv, Elasticsearch 6 and 7 templates, and field documentation
  for the main website. #336
• Generator for the asciidoc rendering of field definitions. #347
• Generator for the Beats fields.ecs.yml file. #379
• Remove many legacy generated files. #399
• Specify static output format for event.duration. #425
• Format port numbers and numeric IDs as strings. #454
• Add example for process.pid and process.ppid. #464, #470