Rewriting adding data long

[ehwenk]

updated adding_data_long.qmd file

• have continued to make this the "exhaustive" resource, to be looked at after going through the tutorials
• simply goes through every metadata section
• have removed two sections that are AusTraits specific - using our GitHub repo and solving duplicates across studies. The GitHub text needs to be reworked into two separate files, one generic for traits.build and the other specific to austraits.build that becomes part of that repo