i18n: add landing page translations (en/ru)

Added/updated translations for:
- howto: step labels
- stats: suppliers desc, countries
- testimonial: quote, author, role
- roles: subtitle, updated benefits
- cta: register, demo buttons
- footer: all countries, offices, products, services, legal

i18n/locales/en/cta.json

@@ -1,8 +1,10 @@
 {
   "cta": {
-    "title": "Ready to Start Trading?",
-    "description": "Join thousands of companies already using Optovia for their deals",
+    "title": "Ready to Get Started?",
+    "description": "Join hundreds of companies already trading on Optovia",
     "start_selling": "Start Selling",
-    "start_buying": "Start Buying"
+    "start_buying": "Start Buying",
+    "register": "Register",
+    "demo": "Request Demo"
   }
 }