chore(et): improve error_tracking documentation

[dubloom]

Description

Improves and corrects documentation in the Error Tracking section of basic_usage.rst

Motivation

While writing the Ruby documentation, I found that the python one was missing some precision on the _INCLUDE env variable.

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[github-actions]

CODEOWNERS have been resolved as:

docs/basic_usage.rst                                                    @DataDog/python-guild

[github-actions]

Bootstrap import analysis

Comparison of import times between this PR and base.

Summary

The average import time from this PR is: 234 ± 6 ms.

The average import time from base is: 233 ± 3 ms.

The import time difference between this PR and base is: 0.5 ± 0.2 ms.

The difference is not statistically significant (z = 2.62).

Import time breakdown

The following import paths have shrunk:

ddtrace.auto 1.689 ms (0.72%)

ddtrace.bootstrap.sitecustomize 1.025 ms (0.44%)

ddtrace.bootstrap.preload 1.025 ms (0.44%)

ddtrace.internal.remoteconfig.client 0.547 ms (0.23%)

ddtrace 0.664 ms (0.28%)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-05-14 11:21:50

Comparing candidate commit 7ca3be2 in PR branch dubloom/fix/error-tracking-do with baseline commit 01bb3a5 in branch main.

Found 0 performance improvements and 5 performance regressions! Performance is the same for 518 metrics, 5 unstable metrics.

scenario:iast_aspects-format_map_aspect

• 🟥 execution_time [+592.183ns; +631.324ns] or [+18.552%; +19.778%]

scenario:iast_aspects-modulo_aspect_for_bytes_bytearray

• 🟥 execution_time [+71.689ns; +95.602ns] or [+7.039%; +9.387%]

scenario:iast_aspects-replace_aspect

• 🟥 execution_time [+724.415ns; +838.002ns] or [+15.905%; +18.399%]

scenario:iast_aspects-strip_aspect

• 🟥 execution_time [+1.451µs; +1.559µs] or [+11.218%; +12.057%]

scenario:telemetryaddmetric-1-distribution-metric-1-times

• 🟥 execution_time [+342.550ns; +413.898ns] or [+11.218%; +13.555%]