chore/add-otlp-docs

Author: scottgerring

docs/design/architecture.md

@@ -5,7 +5,7 @@ This document provides a stable, high-level description of how the OpenTelemetry
 
 > Reference: the [OpenTelemetry Specification](https://opentelemetry.io/docs/specs/otel/) and its [GitHub repository](https://github.com/open-telemetry/opentelemetry-specification/)
 
-## 2 Layered Model
+## 2 Layering
 ```mermaid
 graph TD
     A[Application code] --> B[opentelemetry API]