Added comments and changed to cron

jobs/bump-jenkins-plugins.Jenkinsfile

@@ -1,3 +1,17 @@
+/*
+bump-jenkins-job automates the process of checking for updates to Jenkins plugins, updating the plugin versions in a configuration file, 
+pushing the changes to a Git repository, and opening a pull request for review.
+
+Plugin Update Process:
+
+This job reads a list of plugins from the file plugins.txt in the repository.
+It iterates over each plugin, checks for updates and if a newer version is available, it updates the version in the file.
+For each plugin, it fetches the latest version by querying a URL based on the Jenkins plugin repository structure.
+If an update is found, it modifies the plugins.txt file to reflect the new version.
+The updates in the plugins.txt file are committed and pushed to the pr_branch.
+It also opens a pull request with the updated plugin versions.
+*/
+
 repo = "coreos/fedora-coreos-pipeline"
 fork_repo = "coreosbot-releng/fedora-coreos-pipeline"
 botCreds = "github-coreosbot-releng-token-username-password"
@@ -29,7 +43,7 @@ node {
     properties([
         pipelineTriggers([
             /* Schedule to check once a month */
-            pollSCM('H H 1 * *')
+            cron('H H 1 * *')
         ]),
         buildDiscarder(logRotator(
             numToKeepStr: '100',