Adding README.md for e2e-cli

Author: MichaelGHSeg

e2e-cli/README.md

@@ -0,0 +1,54 @@
+# analytics-java e2e-cli
+
+E2E test CLI for the [analytics-java](https://github.com/segmentio/analytics-java) SDK. Accepts a JSON input describing events and SDK configuration, sends them through the real SDK, and outputs results as JSON.
+
+Built with Kotlin (JVM) and packaged as a fat jar via Maven.
+
+## Setup
+
+```bash
+mvn package -pl e2e-cli -am
+```
+
+## Usage
+
+```bash
+java -jar e2e-cli/target/e2e-cli-*-jar-with-dependencies.jar --input '{"writeKey":"...", ...}'
+```
+
+## Input Format
+
+```jsonc
+{
+  "writeKey": "your-write-key",       // required
+  "apiHost": "https://...",           // optional — SDK default if omitted
+  "sequences": [                      // required — event sequences to send
+    {
+      "delayMs": 0,
+      "events": [
+        { "type": "track", "event": "Test", "userId": "user-1" }
+      ]
+    }
+  ],
+  "config": {                         // optional
+    "flushAt": 250,
+    "flushInterval": 10000,
+    "maxRetries": 3,
+    "timeout": 15
+  }
+}
+```
+
+Note: Java is a server-side SDK — there is no CDN settings fetch, so `cdnHost` does not apply.
+
+## Output Format
+
+```json
+{ "success": true, "sentBatches": 1 }
+```
+
+On failure:
+
+```json
+{ "success": false, "error": "description", "sentBatches": 0 }
+```