add more variable names to -info.xlsx attribute template

[sbeaulieu]

we could add more of our commonly used variable names (column headers) to the -info.xls attribute template and then direct providers to this when they are creating new data tables

[joefutrelle]

@sbeaulieu which variables should we include?

[sbeaulieu]

Another idea would be to - not - add to the Excel template but rather to have a text file compiling attributes from our EDI packages. Text files are easier for version control and to see quickly in GitHub. It may be good to consider this for keywords and custom units too.