Update documentation links or mix in documentation from external sources.

IBM's former AppDev wiki is dead and has been moved to https://ds-infolib.hcltechsw.com/ldd/appdevwiki.nsf/xpDocViewer.xsp?lookupName=Dev+Guide+topics#action=openDocument&res_title=Extending_the_navigation_bar&content=pdcontent&sa=true

Can you fix the documentation site to point to the new place or even better move information into this repository directly.