docs: add users phpseclib (facebook#6022)

Author: terrafrost

website-1.x/data/users.js

@@ -518,6 +518,13 @@ const users = [
     fbOpenSource: false,
     pinned: false,
   },
+  {
+    caption: 'phpseclib',
+    image: '/img/users/phpseclib.png',
+    infoLink: 'https://phpseclib.com/',
+    fbOpenSource: false,
+    pinned: false,
+  },
   {
     caption: 'pnpm',
     image: '/img/users/pnpm.svg',