[backup.xml]: Not all available system tasks are listed under available tasks

[duncdrum]

Describe the problem
backup.xml omits available tasks, which appear in a code listing on configuration.xml these are all omitted:

 <parameter name="dir" value="backup"/>
 <parameter name="suffix" value=".zip"/>
 <parameter name="prefix" value="backup-"/>
 <parameter name="collection" value="/db"/>
 <parameter name="user" value="admin"/>
 <parameter name="password"/>
 <parameter name="zip-files-max" value="28"/>

In addition the inline comments mention output-dir which either clashes with dir here or is another parameter.

see eXist-db/exist#3238
see #308

Please provide the following

• exist-db version: 5.2.0
• documentation version: 5.2.0-SNAPSHOT