[docs][e2e] Introduce README for e2e tests (apache#937)

paimon-e2e-tests/README.md

@@ -0,0 +1,40 @@
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+# End-to-End (E2E) Testing
+This directory contains end-to-end (e2e) testing for Paimon, which ensures users can run Paimon as expected across the entire stack.
+
+## Run e2e tests Locally
+Currently, e2e supports docker environment only. You need to do some preparations before running e2e tests.
+
+### Prepare
+1. Install docker engine or desktop in your local environment.
+2. Start docker daemon.
+3. Set `rootLogger.level` to `INFO` at `paimon-e2e-tests/src/test/resources/log4j2-test.properties` if you need to debug. 
+
+### Execution
+1. Build with Flink-versioned profiles, like flink-1.17. The default Flink main version is declared in the parent `pom.xml` by `<test.flink.main.version>` tag.
+
+```Bash
+mvn clean install -DskipTests -Pflink-1.17
+```
+2. Run e2e tests
+```Bash
+mvn test -pl paimon-e2e-tests -Pflink-1.17
+```