Added information about it to both man and help.
Change prepared in upstream:
The --riskcheck option now has detailed description, both in man page and --help text:
--riskcheck Return the highest reported level of risk or result
related to system upgrade. Run Preupgrade Assistant
first - assessment of the system needs to be performed
before using this option. When this option is used in
concert with --verbose option, summary of the risks
are printed to STDOUT. If the --verbose option is used
once, just HIGH and EXTREME risks are printed. If it
is used twice, all the risks are printed.
0 ... SLIGHT or MEDIUM risk or needs_inspection,
fixed, informational, not_applicable, not_selected,
not_checked or pass result.
1 ... HIGH risk or needs_action result.
2 ... EXTREME risk or error or fail result.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.