rm Tidelift linkage

Tidelift has been an amazing sponsor but now that they're paying me $25
/ month vs $400 / month I can't justify all of the concessions that
they've been getting. I wouldn't create a link on phpseclib.com to
promote anyone for $25 / month and Tidelift is no exception.

Even if this change means I stop receiving Tidelift sponsorship I will
still always be grateful for the financial support I have received from
them.

Related:

https://phpc.social/@ramsey/112165306934938166
https://phpc.social/@sebastian/112211953974965066

Author: terrafrost

docs/for-enterprise.md

@@ -41,8 +41,7 @@ const siteConfig = {
     {doc: 'why', label: 'Docs'},
     {href: 'https://api.phpseclib.com', label: 'API'},
     {href: 'https://stackoverflow.com/questions/tagged/phpseclib', label: 'Support'},
-    {href: 'https://github.com/phpseclib/phpseclib', label: 'GitHub'},
-    {doc: 'for-enterprise', label: 'For Enterprise'}
+    {href: 'https://github.com/phpseclib/phpseclib', label: 'GitHub'}
   ],
 
   algolia: {