[feature] add st web basedir path (#108)

README.md

@@ -43,6 +43,7 @@ You have two ways to get the SeaTunnel installer package. Build from source code
 ##### 2.1.1 Build from source code and deploy
 * Get the source package from https://seatunnel.apache.org/download or https://github.com/apache/seatunnel.git
 * Build installer package use maven command `./mvnw -U -T 1C clean install -DskipTests -D"maven.test.skip"=true -D"maven.javadoc.skip"=true -D"checkstyle.skip"=true -D"license.skipAddThirdParty" `
+* After building, it is necessary to set an environment variable `ST_WEB_BASEDIR_PATH` to represent the location of the data source shade package. A custom class loader will be used to load the data source shade package based on this. For example: `ST_WEB_BASEDIR_PATH=/seatunnel-web-dist/target/apache-seatunnel-web-1.0.0-SNAPSHOT/`
 * Then you can get the installer package in `${Your_code_dir}/seatunnel-dist/target`, For example:`apache-seatunnel-2.3.3-SNAPSHOT-bin.tar.gz`
 * Run `tar -zxvf apache-seatunnel-2.3.3-SNAPSHOT-bin.tar.gz` to unzip the installer package.
 * Run `cd apache-seatunnel-2.3.3-SNAPSHOT & sh bin/seatunnel-cluster.sh -d` to run the SeaTunnel Zeta Engine Server.