docs: add Quick Start section with Docker command (jaegertracing#7945)

Author: njg7194

README.md

@@ -18,6 +18,26 @@
 
 💥💥💥 Jaeger v2 is out! Read the [blog post](https://medium.com/jaegertracing/jaeger-v2-released-09a6033d1b10) and [try it out](https://www.jaegertracing.io/docs/latest/getting-started/).
 
+## Quick Start
+
+Get Jaeger running in seconds with Docker:
+
+```bash
+# Run Jaeger all-in-one (includes UI, collector, query, and in-memory storage)
+docker run --rm --name jaeger \
+  -p 16686:16686 \
+  -p 4317:4317 \
+  -p 4318:4318 \
+  jaegertracing/jaeger:latest
+
+# Access the UI at http://localhost:16686
+# Send traces via OTLP: gRPC on port 4317, HTTP on port 4318
+```
+
+For production deployments and more options, see the [Getting Started Guide](https://www.jaegertracing.io/docs/latest/getting-started/).
+
+## Architecture
+
 ```mermaid
 graph TD
     SDK["OpenTelemetry SDK"] --> |HTTP or gRPC| COLLECTOR