Document '--safety' option in help (danmar#7300)

Author: the-risk-taker

cli/cmdlineparser.cpp

@@ -1870,6 +1870,9 @@ void CmdLineParser::printHelp() const
         "    --rule=<rule>        Match regular expression.\n"
         "    --rule-file=<file>   Use given rule file. For more information, see:\n"
         "                         http://sourceforge.net/projects/cppcheck/files/Articles/\n"
+        "    --safety             Enable safety-certified checking mode: display checker summary, enforce\n"
+        "                         stricter checks for critical errors, and return a non-zero exit code\n"
+        "                         if such errors occur.\n"
         "    --showtime=<mode>    Show timing information.\n"
         "                         The available modes are:\n"
         "                          * none\n"