add info on jstl.jar and standard.jar

i2p2www/pages/site/docs/spec/plugin.html

@@ -455,6 +455,13 @@ no matter how old or how new the original installation:
  commons-logging.jar, commons-el.jar, wrapper.jar, systray.jar, systray4j.jar
 <p>
 
+The following jars in $I2P/lib can be assumed to be present for all I2P installations,
+no matter how old or how new the original installation,
+but are not necessarily in the classpath:
+<p>
+ jstl.jar, standard.jar
+<p>
+
  Anything not listed above may not be present in everybody's classpath, even if you
  have it in the classpath in YOUR version of i2p.
  If you need any jar not listed above, add $I2P/lib/foo.jar to the classpath specified