Rebrand to 'For Enterprise'

docs/_templates/tidelift-sidebar.html

-<h3 class="donation">Professional support</h3>
+<h3 class="donation">For Enterprise</h3>
 
 <p>
 Professionally-supported {{ project }} is available with the
-<a href="https://tidelift.com/subscription/pkg/pypi-{{ project }}?utm_source=pypi-{{ project }}&utm_medium=readme">Tidelift Subscription</a>.
+<a href="https://tidelift.com/subscription/pkg/pypi-{{ project }}?utm_source=pypi-{{ project }}&utm_medium=referral">Tidelift Subscription</a>.
 </p>