First cut at single writer principle. (#1574)
First cut at single writer principle. (#1574)

* First cut at single writer principle.

* Fixes from reviews.

* Fixes from lint.

* Apply suggestions from code review

Co-authored-by: Tigran Najaryan <d4b56ad22c7b19843c9455a85ff7cbd0f6cbc202@users.noreply.github.com>

* Fixes from review.

* Add missing temporality section to help justify overlap section.

* Fix markdown lint.

* Fixes from review.

* Update specification/metrics/datamodel.md

Co-authored-by: Reiley Yang <30492acf0f6ef8016cbaa2354294f909e563626a@microsoft.com>

* Update specification/metrics/datamodel.md

Co-authored-by: Reiley Yang <30492acf0f6ef8016cbaa2354294f909e563626a@microsoft.com>

* Fixes from review.

* Update specification/metrics/datamodel.md

Co-authored-by: Max Edmands <5a7c0b8e165d1a98c0f0ec561871fb8594a42dc2@users.noreply.github.com>

* Update specification/metrics/datamodel.md

Co-authored-by: Max Edmands <5a7c0b8e165d1a98c0f0ec561871fb8594a42dc2@users.noreply.github.com>

Co-authored-by: Tigran Najaryan <d4b56ad22c7b19843c9455a85ff7cbd0f6cbc202@users.noreply.github.com>
Co-authored-by: Reiley Yang <30492acf0f6ef8016cbaa2354294f909e563626a@microsoft.com>
Co-authored-by: Max Edmands <5a7c0b8e165d1a98c0f0ec561871fb8594a42dc2@users.noreply.github.com>
Co-authored-by: Sergey Kanzhelev <dd2a78e617335ac05535a01af404ce3eb19c30fd@live.com>
open-telemetry/opentelemetry-specification,open-telemetry/opentelemetry-specification