User guide and help text updates

Details  of --config  command line  option. Note  that low  confidence
decodes '?'  are not spotted and  more generic text for  --help command
line option now derived from CMakeLists description strings.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8005 ab8295b8-cf94-4d9e-aec4-7959e3be5d79

main.cpp

@@ -110,7 +110,7 @@ int main(int argc, char *argv[])
 
 #if QT_VERSION >= 0x050200
       QCommandLineParser parser;
-      parser.setApplicationDescription ("\nJT65, JT9, JT4, MSK144, QRA64, ISCAT & WSPR Weak Signal Communications Program.");
+      parser.setApplicationDescription ("\n" PROJECT_SUMMARY_DESCRIPTION);
       auto help_option = parser.addHelpOption ();
       auto version_option = parser.addVersionOption ();