change all $env to ${}

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

plugins/jenkins/README.md

@@ -29,15 +29,13 @@ proxy:
     target: 'http://localhost:8080' # your Jenkins URL
     changeOrigin: true
     headers:
-      Authorization:
-        $env: JENKINS_BASIC_AUTH_HEADER
+      Authorization: Basic ${JENKINS_BASIC_AUTH_HEADER}
 ```
 
 4. Add an environment variable which contains the Jenkins credentials, (note: use an API token not your password). Here user is the name of the user created in Jenkins.
 
 ```shell
-HEADER=$(echo -n user:api-token | base64)
-export JENKINS_BASIC_AUTH_HEADER="Basic $HEADER"
+export JENKINS_BASIC_AUTH_HEADER=$(echo -n user:api-token | base64)
 ```
 
 5. Run app with `yarn start`