Modify law dpoa example

[xaviertintin]

Set up a PFNano-production-type workflow on open data in open data environment with:

• PFNano-production step (either faking it with POET or NanoAOD backport trial)
• “analysis”/plotting step with the proposed tools (i.e. RDataFrame and Coffea)

Note: This must reflect the same workflow process done with GitHub Actions. (In this same repository)

[xaviertintin]

“analysis”/plotting step with the proposed tools (i.e. RDataFrame and Coffea) is complete