[docs] Improve pipeline section docs

[PadreSVK]

based on information provided:

• https://docs.google.com/document/d/1NeheFG7DmcUYo_h2vLtNRlia9x5wOJMlV4QKEK05FhQ/edit?tab=t.0#heading=h.g6rvvz3l271i
• https://github.com/open-o11y/opentelemetry-collector-testing/blob/master/docs/design.md#receivers

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: PadreSVK / name: Patrik Švikruha (f62946d, de9f9ed)
• ✅ login: opentelemetrybot / name: OpenTelemetry Bot (ef80965)

[mx-psi]

Thank you! Left one comment, I am not a technical writer so it may be that others have a better suggestion here

[svrnm]

Beyond the suggested change from @mx-psi this looks good to me. If you can fix that, we can merge it in

[tiffany76]

Hi @PadreSVK, please take a look at the most recent suggested changes so we can move this PR forward. Thanks!

[tiffany76]

@svrnm, does this one look good to you?

[chalin]

/fix:format

[opentelemetrybot]

You triggered fix:format action run at https://github.com/open-telemetry/opentelemetry.io/actions/runs/13574933410

[opentelemetrybot]

fix:format was successful.

IMPORTANT: (RE-)RUN /fix:all to ensure that there are no remaining check issues.

[chalin]

@tiffany76 wrote:

@svrnm, does this one look good to you?

Since @svrnm is kinda out, and he only wanted to ensure that @mx-psi's comment was addressed; and @mx-psi has approved, let's consider this implicitly approved by @svrnm.

[opentelemetrybot]

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