Document DPS configuration options

[wildintellect]

Users are confused about what options are available in algorithm configuration and what that implies for how and algorithm main shell script is then written. e.g. File(s) vs inputs

Likely location https://docs.maap-project.org/en/latest/getting_started/running_at_scale.html#Register-an-Algorithm but could be a new page under technical tutorials.

Acceptance Criteria

• [ ] Algorithm Configuration options
• [ ] How to use input/reference variables in shell scripts (DPS jobs)

See also #278 #274

[rtapella]

migrated to https://github.com/MAAP-Project/maap-documentation/issues/400

[rtapella]

added to #400