Reorg manual tracing JS docs based on SDK (#1445)

* Simplify and make js manual doc more correct

* Reorganize JS manual tracing docs and linkify

* PR feedback

* PR feedback

* Just use CJS modules & PR feedback

* Update content/en/docs/instrumentation/js/instrumentation.md

Co-authored-by: Austin Parker <[email protected]>

* Some more changes from PR feedback

* Triple hash

* Move registerInstrumentations snippet above exporter config

Co-authored-by: Patrice Chalin <[email protected]>
Co-authored-by: Austin Parker <[email protected]>