Update freenet.l10n.en.properties

FIX errors in logs;
 
The default translation for Bookmarks.Defaults.Description.Fniki hasn't been found!
jvm 1    | 
jvm 1    | java.lang.Exception
jvm 1    | 	at freenet.l10n.BaseL10n.getDefaultString(BaseL10n.java:466)
jvm 1    | 	at freenet.l10n.BaseL10n.getString(BaseL10n.java:411)
jvm 1    | 	at freenet.l10n.BaseL10n.getString(BaseL10n.java:384)
jvm 1    | 	at freenet.clients.http.bookmark.BookmarkItem.getDescription(BookmarkItem.java:264)
jvm 1    | 	at freenet.clients.http.WelcomeToadlet.addCategoryToList(WelcomeToadlet.java:89)
jvm 1    | 	at freenet.clients.http.WelcomeToadlet.addCategoryToList(WelcomeToadlet.java:102)
jvm 1    | 	at freenet.clients.http.WelcomeToadlet.handleMethodGET(WelcomeToadlet.java:409)
jvm 1    | 	at freenet.clients.http.ToadletContextImpl.callToadletMethod(ToadletContextImpl.java:711)
jvm 1    | 	at freenet.clients.http.ToadletContextImpl.handle(ToadletContextImpl.java:648)
jvm 1    | 	at freenet.clients.http.SimpleToadletServer$SocketHandler.run(SimpleToadletServer.java:1032)
jvm 1    | 	at freenet.support.PooledExecutor$MyThread.innerRun(PooledExecutor.java:248)
jvm 1    | 	at freenet.support.PooledExecutor$MyThread.realRun(PooledExecutor.java:188)
jvm 1    | 	at freenet.support.io.NativeThread.run(NativeThread.java:129)