Clarify default value for OTEL_EXPORTER_OTLP_TIMEOUT to include units…

[ta-ke-inf]

Description

Clarify the unit for the documented default value of OTEL_EXPORTER_OTLP_TIMEOUT in the SDK environment variables docs.

The current docs show Default: 10 without stating the unit, which can lead to operators misinterpreting the value (e.g., 10ms vs 10s). This PR updates only the default line to make the unit explicit while keeping the surrounding wording consistent with existing env var docs.

Fixes #4858

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• Built the docs locally with Sphinx
• python -m pip install -r docs-requirements.txt
• cd docs && python -m sphinx -b html -D master_doc=sdk/environment_variables . _build/html_envvars

Does This PR Require a Contrib Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

• ❌ - login: @ta-ke-inf / name: Takeguchi . The commit (3aa10ad) is not authorized under a signed CLA. Please click here to be authorized. For further assistance with EasyCLA, please submit a support request ticket.