Progress on documentation

Documentation for flagging .Rmd's update:

This is a huge PR because of the HTMLs that I am adding.
No pie charts yet
I have not found a good method for adding example plots for functions that add more than one flag.
I am currently working on add_seasonal_flag.Rmd, so that one might be weird.

General PR updates:

Worked out some issues that I was getting when I pulled that had to do with some plotting functions and file paths.
added df_list arg to plotting functions so that we can explore data that is not just in all_data_flagged list.
saved the data before it has been flagged into its own RDS
Added the add_repeat_flag() function when to the flagging step
Added the generate_flag_report() step to the exploration .Rmd as I found it useful there.
Minor alterations to some scripts (just removing some empty lines)
add_seasonal_flag() step
- Removed some columns that were added onto the df because that broke the plotting functions
- updated the sensor handling method.

rossyndicate / poudre_sonde_network