Minor fixes to OTLP collector page

[asopkin]

What does this PR do? What is the motivation?

1. Renames to the Pure OTel Collector because "Community Collector" had a negative connotation
2. Adjusts nesting after feedback that it was confusing that the other OTel options were buried under "Other setup options"
3. Some minor changes to reframe the pure OTel Collector page to focus more on OTel concepts rather than Datadog-specific terms.

Merge readiness

• Ready for merge

For Datadog employees:

• ⚠️ Your branch name MUST follow the <name>/<description> convention and include the forward slash (/). If you've already created your PR with an incorrect branch name, please rename your branch and open a fresh PR.
• 🤖 New: Comment with /review to run an automated check that catches common issues before a Documentation team member reviews your PR.

AI assistance

Additional notes

[asopkin]

/review

[github-actions]

🤖 Automated review by Claude. AI-generated; verify before acting.

Terminology inconsistency: the file title changed from "Community" to "Pure OpenTelemetry Collector", but references to "Community OTel Collector"/"Community OpenTelemetry Collector" remain in several body locations. See inline comment on the title for the specific lines.

One minor style suggestion on the Unified Service Tagging paragraph.

_{Reviewed 584c76b1b0947a79d39ab88d567be4921a51769e — workflow run}

[github-actions]

Issue: The title (and description at L7) now use "Pure OpenTelemetry Collector", but the body still says "Community" in several places that were left unchanged:

• L22 (Overview intro): "...using the Community OpenTelemetry Collector, which is based on..."
• L36 (Prerequisites): "...see the [feature compatibility table][7] under OTel SDK + Community OTel Collector."
• L934 (info alert under dd-otel-metric-config): "The recommended Community OTel Collector configuration uses..."

If the rename is intentional, please update these occurrences (and coordinate the corresponding heading rename in hugo/content/en/opentelemetry/compatibility.md, which still uses "OTel SDK + Community OTel Collector" — otherwise the L36 link anchor breaks) so the naming is consistent.

[github-actions]

Preview links (active after the build_preview check completes)

Renamed files

• https://docs-staging.datadoghq.com/asopkin/pure-otlp-pipeline-fixes/opentelemetry/setup/collector_exporter/pure_otlp_collector

Modified Files

• https://docs-staging.datadoghq.com/asopkin/pure-otlp-pipeline-fixes/opentelemetry/compatibility
• https://docs-staging.datadoghq.com/asopkin/pure-otlp-pipeline-fixes/opentelemetry/guide/instrument_unsupported_runtimes

[rtrieu]

some minor feedback for your review - please request a re-review when ready!