Build: Update external javadoc links

Add description to gradle update tasks
Add note about jetty versions

build.properties

@@ -9,15 +9,16 @@
 
 # Javadocs
 # Note: Include the trailing slash! Don't surround the URL in quotes!
-javasedocs.url=http://docs.oracle.com/javase/7/docs/api/
-javaeedocs.url=http://docs.oracle.com/javaee/7/api/
+javasedocs.url=https://docs.oracle.com/javase/8/docs/api/
+javaeedocs.url=https://docs.oracle.com/javaee/7/api/
 # The following link is for 9.4.x
 #jettydocs.url=http://download.eclipse.org/jetty/stable-9/apidocs/
-jettydocs.url=http://download.eclipse.org/jetty/9.2.21.v20170120/apidocs/
-wrapperdocs.url=http://wrapper.tanukisoftware.com/jdoc/
+# last one available on archive.eclipse.org
+jettydocs.url=https://archive.eclipse.org/jetty/9.3.9.v20160517/apidocs/
+wrapperdocs.url=https://wrapper.tanukisoftware.com/jdoc/
 # these are only for unit test javadocs
 i2pdocs.url=http://docs.i2p-projekt.de/javadoc/
-junitdocs.url=http://junit.org/apidocs/
+junitdocs.url=https://junit.org/junit5/docs/current/api/
 # This will go in the jar manifests
 build.built-by=unknown
 

build.xml

@@ -10,7 +10,10 @@
      -->
     <property file="override.properties"/>
     <property file="build.properties"/>
-    <!--  When changing, also change javadoc URL in build.properties, and checksum in apps/jetty/build.xml -->
+    <!--  When changing, also change javadoc URL in build.properties,
+          and checksum in apps/jetty/build.xml
+          and versions in apps/jetty/build.gradle
+     -->
     <property name="jetty.ver" value="9.3.29.v20201019" />
     <property name="tomcat.ver" value="9.0.40" />
 

gradle/update.gradle

@@ -84,6 +84,7 @@ task prepUpdate(type: Copy) {
 }
 
 task updaterRouter(type: Zip) {
+    description 'makes an i2pupdate.zip file containing core and router jars only'
     dependsOn prepUpdateRouter
     archiveName 'i2pupdate.zip'
     destinationDir file('.')
@@ -91,6 +92,7 @@ task updaterRouter(type: Zip) {
 }
 
 task updaterSmall(type: Zip) {
+    description 'makes an i2pupdate.zip file with a subset of the resources'
     dependsOn prepUpdateSmall
     archiveName 'i2pupdate.zip'
     destinationDir file('.')
@@ -98,6 +100,7 @@ task updaterSmall(type: Zip) {
 }
 
 task updater(type: Zip) {
+    description 'makes an i2pupdate.zip file'
     dependsOn prepUpdate
     archiveName 'i2pupdate.zip'
     destinationDir file('.')