Add branch condition to Discord notification stage

The Discord notification stage now runs only on 'main' or 'master' branches. This helps to avoid unnecessary notifications for feature or bugfix branches.

Jenkinsfile

@@ -12,6 +12,12 @@ pipeline {
             }
         }
         stage('discord') {
+            when {
+                anyOf {
+                    branch 'main'
+                    branch 'master'
+                }
+            }
             steps {
                 discordSend description: "Build: ${BUILD_NUMBER}", showChangeset: true, result: currentBuild.currentResult, title: currentBuild.fullProjectName, webhookURL: env.discordwebhook
             }