fix use of pluto change files

[damonmcc]

changes

• generalize approach to getting pluto change zip file and csv files to accommodate filename changes introduced in https://github.com/NYCPlanning/db-pluto/pull/425
• preserve backwards compatibility by always looking for both new and old sets of filename
• use pluto_changes_applied.csv for Review Manual Corrections section of PLUTO QAQC page
• simplify uses of DigitalOceanClient in all helpers.py files
• add an example.env file
• impore intro section of PLUTO page
  • remove badges from PLUTO page (they already exist in PLUTO repo readme and can be misleading)
  • incorporate text changes from Te's PR https://github.com/NYCPlanning/data-engineering-qaqc/pull/253
• update readme dev details

[damonmcc]

made and tested replacing correction with changes in both text and code