Use .md for outro too

Author: chalin

content/en/docs/languages/cpp/exporters.md

@@ -353,7 +353,7 @@ void InitTracer()
 }
 ```
 
-{{% include outro `https://opentelemetry-cpp.readthedocs.io/en/latest/otel_docs/classopentelemetry_1_1sdk_1_1trace_1_1SpanExporter.html` %}}
+{{% include outro.md `https://opentelemetry-cpp.readthedocs.io/en/latest/otel_docs/classopentelemetry_1_1sdk_1_1trace_1_1SpanExporter.html` %}}
 
 {{< tabpane text=true >}} {{% tab Batch %}}
 

content/en/docs/languages/js/exporters.md

@@ -345,7 +345,7 @@ const sdk = new opentelemetry.NodeSDK({
 
 {{% /tab %}} {{< /tabpane >}}
 
-{{% include outro `https://open-telemetry.github.io/opentelemetry-js/interfaces/_opentelemetry_sdk_trace_base.SpanExporter.html` %}}
+{{% include outro.md `https://open-telemetry.github.io/opentelemetry-js/interfaces/_opentelemetry_sdk_trace_base.SpanExporter.html` %}}
 
 {{< tabpane text=true >}} {{% tab TypeScript %}}
 

content/en/docs/languages/python/exporters.md

@@ -306,7 +306,7 @@ trace.set_tracer_provider(provider)
 
 {{% /tab %}} {{< /tabpane >}}
 
-{{% include outro `https://opentelemetry-python.readthedocs.io/en/latest/sdk/trace.export.html#opentelemetry.sdk.trace.export.SpanExporter` %}}
+{{% include outro.md `https://opentelemetry-python.readthedocs.io/en/latest/sdk/trace.export.html#opentelemetry.sdk.trace.export.SpanExporter` %}}
 
 ```python
 from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter