ci: add genaration of build.json matadate file

Useful for debugging missing deployments.

Signed-off-by: Jakub Sokołowski <jakub@status.im>

Jenkinsfile

@@ -1,3 +1,6 @@
+#!/usr/bin/env groovy
+library 'status-jenkins-lib@v1.8.8'
+
 pipeline {
   agent { label 'linux' }
 
@@ -27,9 +30,12 @@ pipeline {
     }
 
     stage('Build') {
-      steps {
+      steps { script {
         sh 'yarn build'
-        sh "echo ${env.PROD_SITE} > build/CNAME"
+        dir('build') {
+          sh "echo ${env.PROD_SITE} > CNAME"
+          jenkins.genBuildMetaJSON()
+        } }
       }
     }