docs(node): support "stable"/"preview" release level (#1312) (#656)
docs(node): support "stable"/"preview" release level (#1312) (#656)

Source-Link: https://github.com/googleapis/synthtool/commit/8d2c953d08984586180da7e285eeca19cc48729f
Post-Processor: c86da0eb35ae387347c523a1f7f5f619652373a7@sha256:5ed10ba99cd1ea8c3a0f29b4c53e8a2723a101952705baed6b61783111c64c1c
Co-authored-by: Owl Bot <7f39581e9a7ddb69f3fa3e6fc69a582ea2916fc9@users.noreply.github.com>
googleapis/google-cloud-node,googleapis/google-cloud-node,googleapis/google-cloud-node,googleapis/google-cloud-node