Update API docs for beta (#855)
Update API docs for beta (#855)

* docs: update API docs for beta

* chore: remove duplicate wording

* chore: review comments

* Update packages/opentelemetry-api/README.md

Co-Authored-By: Mayur Kale <7b800b27b32ee7e0fdb93e2c1dbfb3464ab1d5e6@google.com>

Co-authored-by: Mayur Kale <7b800b27b32ee7e0fdb93e2c1dbfb3464ab1d5e6@google.com>
open-telemetry/opentelemetry-js,open-telemetry/opentelemetry-js-contrib,open-telemetry/opentelemetry-js,open-telemetry/opentelemetry-js,open-telemetry/opentelemetry-js-contrib,open-telemetry/opentelemetry-js,open-telemetry/opentelemetry-js-contrib,open-telemetry/opentelemetry-js-contrib