Clarify Sentry authentication header format in OpenTelemetry documentation

- Updated the formatting of the Sentry authentication header description to ensure proper usage of curly braces around the public key placeholder in the OpenTelemetry data exporting instructions.

Author: nevikashah

src/content/docs/workers/observability/exporting-opentelemetry-data/sentry.mdx

@@ -69,7 +69,7 @@ To configure your logs destination, click **Add destination** and configure the
    - **OTLP Endpoint**: Your Sentry OTLP logs endpoint (e.g., `https://{HOST}/api/{PROJECT_ID}/integration/otlp/v1/logs`)
    - **Custom Headers**: Add the Sentry authentication header:
      - Header name: `x-sentry-auth`
-     - Header value: `sentry sentry_key={SENTRY_PUBLIC_KEY}` where {SENTRY_PUBLIC_KEY} is your Sentry project's public key
+     - Header value: `sentry sentry_key={SENTRY_PUBLIC_KEY}` where `{SENTRY_PUBLIC_KEY}` is your Sentry project's public key
 
 
 ## Step 4: Configure your Worker