Add initial version of C++ Getting Started, Manual & Exporters

[svrnm]

Since I was playing around with c++ opentelemetry anyways I thought it might be a nice exercise to get the docs drafted for it. This first version is not ideal, but hopefully a good start:

• Getting Started leads people to have a http_server & http_client up and running
• Manual & Exporters are mostly text copys from https://opentelemetry-cpp.readthedocs.io/, they still lack some context with the getting started

Preview: https://deploy-preview-1857--opentelemetry.netlify.app/docs/instrumentation/cpp/getting-started/

[svrnm]

related: #1815, #1816, #1817

[lalitb]

Thanks for the efforts. This looks good for the initial version.

[svrnm]

@lalitb , @cartermp thanks for your reviews, I applied all of your suggestions, hope it looks good now :)

[lalitb]

Looks good. Thanks for adding this.

[cartermp]

Very good!

[cartermp]

@svrnm I will leave it up to you if you wisht o close the three linked issues. It's arguable that each of these docs need more work to effectively close each, but this is considerable progress and...I like making issues get closed.

[svrnm]

@svrnm I will leave it up to you if you wisht o close the three linked issues. It's arguable that each of these docs need more work to effectively close each, but this is considerable progress and...I like making issues get closed.

I think we can close them, followup improvements can have their own issues.