Update urls in documentation from ecosystem to new github pages location

[woodsp-ibm]

There are a number of files with links to the docs in qiskit.org/ecosystem that need updating to the new location as follow-up after #115

• setup.py (see Update setup, readme urls #125)
• readme.md (see Update setup, readme urls #125)

and also

• a number of tutorial notebooks Update intersphinx links and others #142 updated links except for Aer so now only 01 and 03 tutorials need updating for the couple of Aer links in each once the Aer docs are deployed in a new location. Aer urls updated by Update links to Aer docs now that its on github pages #147

and I listed this separately since the notebooks have links to Aer and Nature for which maybe its better to wait until they are all migrated off ecosystem and update them just the once. The redirects will suffice for now.