Clarify current state of browser support in the README

[pichlermarc]

Currently, browser support of the packages in this repo is not considered production-ready

We should:

• clarify this in our README.md and set expectations accordingly.
• add a note similar to the one proposed in Add a warning to browser getting started opentelemetry.io#3125 on how to help/improve the state of the project in this regard.

[chalin]

The status given in Status and Releases of the JS page of OTel.io is:

Would it make sense to change it to the following?

Some heading	Traces	Metrics	Logs
Node.js	Stable	Stable	Development
Browser	Experimental	Experimental	Development

/cc @svrnm @cartermp

[svrnm]

open-telemetry/opentelemetry.io#3125 got merged, you can take the wording used on the website for the README if you like (or come up with better words and let us know and we use them as well)

[pichlermarc]

The status given in Status and Releases of the JS page of OTel.io is:

Would it make sense to change it to the following?
Some heading Traces Metrics Logs
Node.js Stable Stable Development
Browser Experimental Experimental Development

Hmmm 🤔 From my understanding, this matrix always represented the stability of the interface, not the runtime support. I wouldn't rule out that users interpret this in another way, though. I'll ask about this in the SIG Meeting next week to see what others think. 🤔

cc @open-telemetry/javascript-approvers

[pichlermarc]

open-telemetry/opentelemetry.io#3125 got merged, you can take the wording used on the website for the README if you like (or come up with better words and let us know and we use them as well)

thanks, opened #4037. I think this fits in nicely without modifications. 🙂