donate-cpu-server.py: Add explanation how to read timing list (#2315)

* Add explanation how to read timing list

* fixed HTML

tools/donate-cpu-server.py

@@ -620,6 +620,8 @@ def timeReport(resultPath: str) -> str:
                     '{:.2f}'.format(time_factor).rjust(column_widths[3]) + '\n'
             break
 
+    html += '\n'
+    html += '(listed above are all suspicious timings with a factor <0.50 or >2.00)\n'
     html += '\n'
     if total_time_base > 0.0:
         total_time_factor = total_time_head / total_time_base