Fixed various links (for new web page).

README.md

docs/api.rst

docs/api_tutorial.md

docs/client/cli_use_cases.rst

docs/client/install.rst

docs/conf.py

docs/introduction.md

docs/metainfo.rst

docs/upload.rst

examples/api_use.py

examples/api_use_authenticated.py

gui/public/env.js

gui/src/components/About.js

gui/src/components/App.js

gui/src/components/metaInfoBrowser/MetaInfoBrowser.js

gui/src/components/uploads/UploadPage.js

gui/src/config.js

nomad/cli/client/statistics.py

nomad/config.py

nomad/doi.py