Add comments to Jenkinsfile

Jenkinsfile

@@ -1,12 +1,25 @@
 pipeline {
     agent any
+
+
+    // We'll be running in a custom Docker image, but could be a ready-made
+    // image from DockerHub
+    //
+    // agent {
+    //    docker {
+    //        image 'loxygen/arch-latex'
+    //    }
+    // }
+
     stages {
         stage('Test') {
             steps {
                script {
+                  // Custom Docker image, see Dockerfile
                   def customImage = docker.build("paper-cutter:${env.BUILD_ID}")
                   customImage.inside() {
                       dir('test') {
+                        // The user under which the job is run does not have a proper home directory (!)
                         sh 'export PATH="$PATH:/usr/bin/vendor_perl"; export fakehomedir=`pwd`/fakehome; rm -rf $fakehomedir; mkdir $fakehomedir; export HOME=$fakehomedir; git config --global user.email "testing@testing.invalid"; git config --global user.name "testing"; bash run_tests.sh'
                       }
                   }