OTEL article could use more information to help coding

### Type of issue

Missing information

### Description

The article works, but might cause someone to do a bit of trial and error. Here's what I observed:

- Using namespaces would be helpful at the start.

```csharp
using System.Diagnostics;
using System.Diagnostics.Metrics;
using OpenTelemetry;
using OpenTelemetry.Metrics;
using OpenTelemetry.Trace;
```

- Running the example website project outputs a different port than used in the article. Instructions that tell the user that when running the project, the port is output to the screen and that's the one to use with the curl command.

- package version is now 1.17.0.

- The order of steps feels wrong, it has you ping-pong around the source code. You're not running the project in between, so there is no reason to do this. It should order things as they end up appearing in the file, this way the user is troubled with trying to inject lines before X and after Y.

### Page URL

https://learn.microsoft.com/en-us/dotnet/core/diagnostics/observability-otlp-example

### Content source URL

https://github.com/dotnet/docs/blob/main/docs/core/diagnostics/observability-otlp-example.md

### Document Version Independent Id

806a9a9c-4902-3843-a878-16876df48a1c

### Platform Id

234fd2b5-cb5d-4524-ed50-2a357c55c4e4

### Article author

@tommcdon

### Metadata

* ID: 1397e92b-7324-4840-73ff-b116774f797c
* PlatformId: 234fd2b5-cb5d-4524-ed50-2a357c55c4e4
* Service: **dotnet-fundamentals**

[Related Issues](https://github.com/dotnet/docs/issues?q=is%3Aissue+is%3Aopen+806a9a9c-4902-3843-a878-16876df48a1c)

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[Associated WorkItem - 626679](https://dev.azure.com/msft-skilling/Content/_workitems/edit/626679)