fix: typo in env var name (#95)

Author: rupesh1

openllmetry/configuration.mdx

@@ -53,7 +53,7 @@ For configuring this to different observability platform, check out our [integra
 <Note>
   The OpenTelemetry standard defines that the actual endpoint should always end
   with `/v1/traces`. Thus, if you specify a base URL, we always append
-  `/v1/traces` to it. This is similar to how `OTLP_EXPORTER_OTLP_ENDPOINT` works
+  `/v1/traces` to it. This is similar to how `OTEL_EXPORTER_OTLP_ENDPOINT` works
   in all OpenTelemetry SDKs.
 </Note>