add debugging info to wiki / vignette

you can check the progress of the calibration in several ways:

in data/calib (or the root of your calib if you changed it) there is an assessment.rds file. Download it and run locally: swfcalib::render_assessment(<path to file>). It will generate an assessment html file that shows the advancement of calibration. (no one used it yet so feedback on that is welcome)
the log for the recurring step 1 tells you the wave and iteration you are on. The The default_proposal currently contains: section shows the values in the default proposal. Once a job has finished, it will change this value with the calibrated one
in data/calib/waves/<number of the wave> there is a results.rds file that contains the values proposed and the resulting targets in a data.frame

EpiModel / swfcalib