README: Add missing Perl dependency TimeDate for Date::Parse

.. for command genhtml.  Not to be mixed up with DateTime,
which is also needed (but already documented).

Signed-off-by: Sebastian Pipping <[email protected]>

Author: hartwork

README

@@ -142,6 +142,7 @@ These perl packages include:
   - Module::Load::Conditional
   - Scalar::Util
   - Time::HiRes
+  - TimeDate
 
 If your system is missing any of these, then you may be able to install them
 via: