phpbu: add page (#3226)

pages/common/phpbu.md

@@ -0,0 +1,20 @@
+# phpbu
+
+> A backup utility framework for PHP.
+> More information: <https://phpbu.de>.
+
+- Run backups using the default "phpbu.xml" configuration file:
+
+`phpbu`
+
+- Run backups using a specific configuration file:
+
+`phpbu --configuration={{path/to/configuration_file.xml}}`
+
+- Only run the specified backups:
+
+`phpbu --limit={{backup_task_name}}`
+
+- Simulate the actions that would have been performed:
+
+`phpbu --simulate`