Add documentation in add_cloud_metadata processor about the usage of BEATS_ADD_CLOUD_METADATA_PROVIDERS env var#1380

MichaelKatsoulis merged 2 commits intomainelastic/ingest-docs:mainfrom

document-add_cloud_metadata_providers-env-varelastic/ingest-docs:document-add_cloud_metadata_providers-env-varCopy head branch name to clipboard