Add pages about resources & resource detection to concept & languages

[svrnm]

Add a new page to “concepts“ that talks about resources & detection in a general way

If available&applicable, add a page about resources & resource detection for each language, similar to this one:

• What resources are detected automatically?
• Adding resources via OTEL_RESOURCE_ATTRIBUTES
• Adding resources in code
• Adding a (non default) resource detector (e.g. container)

TODO:

• [ ] Concept
• [ ] C++
• [ ] .NET (WIP, #1795, @cartermp)
• [ ] Erlang/Elixir
• [ ] Go
• [ ] Java
• [x] JavaScript
• [ ] PHP
• [ ] Python
• [ ] Ruby
• [ ] Rust
• [ ] Swift

Note, I added all languages to get started, if this is not applicable for some of them, we can remove them.

[svrnm]

Added also that we need a page that talks about the concept of resources and how they are detected

[theletterf]

Wonder if we could pin this one and simlar, @svrnm

[svrnm]

Wonder if we could pin this one and simlar, @svrnm

I list them here: https://github.com/open-telemetry/opentelemetry.io/issues/3686, but we can also pin some of them directly