docs: Clarify timeout units in env var docs (open-telemetry#4906)

* Clarify timeout units in env var docs

OTLP timeout env vars lacked unit specification, causing confusion.
Added (in seconds) to docs for OTEL_EXPORTER_OTLP_TIMEOUT and related vars.

Fixes open-telemetry#4858

* add changelog entry

Author: MikeGoldsmith

CHANGELOG.md

@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- `opentelemetry-sdk`: Clarify timeout units in environment variable documentation
+  ([#4906](https://github.com/open-telemetry/opentelemetry-python/pull/4906))
 - `opentelemetry-exporter-otlp-proto-grpc`: Fix re-initialization of gRPC channel on UNAVAILABLE error
   ([#4825](https://github.com/open-telemetry/opentelemetry-python/pull/4825))
 - `opentelemetry-exporter-prometheus`: Fix duplicate HELP/TYPE declarations for metrics with different label sets

opentelemetry-sdk/src/opentelemetry/sdk/environment_variables/__init__.py

@@ -263,7 +263,7 @@
 """
 .. envvar:: OTEL_EXPORTER_JAEGER_TIMEOUT
 
-Maximum time the Jaeger exporter will wait for each batch export.
+Maximum time (in seconds) the Jaeger exporter will wait for each batch export.
 Default: 10
 """
 
@@ -350,7 +350,7 @@
 """
 .. envvar:: OTEL_EXPORTER_OTLP_TIMEOUT
 
-The :envvar:`OTEL_EXPORTER_OTLP_TIMEOUT` is the maximum time the OTLP exporter will wait for each batch export.
+The :envvar:`OTEL_EXPORTER_OTLP_TIMEOUT` is the maximum time (in seconds) the OTLP exporter will wait for each batch export.
 Default: 10
 """
 
@@ -698,16 +698,18 @@ def channel_credential_provider() -> grpc.ChannelCredentials:
 """
 .. envvar:: OTEL_EXPORTER_OTLP_TRACES_TIMEOUT
 
-The :envvar:`OTEL_EXPORTER_OTLP_TRACES_TIMEOUT` is the maximum time the OTLP exporter will
+The :envvar:`OTEL_EXPORTER_OTLP_TRACES_TIMEOUT` is the maximum time (in seconds) the OTLP exporter will
 wait for each batch export for spans.
+Default: 10
 """
 
 OTEL_EXPORTER_OTLP_METRICS_TIMEOUT = "OTEL_EXPORTER_OTLP_METRICS_TIMEOUT"
 """
 .. envvar:: OTEL_EXPORTER_OTLP_METRICS_TIMEOUT
 
-The :envvar:`OTEL_EXPORTER_OTLP_METRICS_TIMEOUT` is the maximum time the OTLP exporter will
+The :envvar:`OTEL_EXPORTER_OTLP_METRICS_TIMEOUT` is the maximum time (in seconds) the OTLP exporter will
 wait for each batch export for metrics.
+Default: 10
 """
 
 OTEL_EXPORTER_OTLP_METRICS_INSECURE = "OTEL_EXPORTER_OTLP_METRICS_INSECURE"
@@ -740,8 +742,9 @@ def channel_credential_provider() -> grpc.ChannelCredentials:
 """
 .. envvar:: OTEL_EXPORTER_OTLP_LOGS_TIMEOUT
 
-The :envvar:`OTEL_EXPORTER_OTLP_LOGS_TIMEOUT` is the maximum time the OTLP exporter will
+The :envvar:`OTEL_EXPORTER_OTLP_LOGS_TIMEOUT` is the maximum time (in seconds) the OTLP exporter will
 wait for each batch export for logs.
+Default: 10
 """
 
 OTEL_EXPORTER_JAEGER_CERTIFICATE = "OTEL_EXPORTER_JAEGER_CERTIFICATE"