Add registered trademark symbol

Signed-off-by: Kaur Palang <kaur.palang@brightcodecompany.com>

Author: kpalang

docs/index.md

@@ -5,7 +5,7 @@ layout: home
 hero:
   name: "Open Integration Engine"
   text: "documentation"
-  tagline: An open source fork of the now closed-source Mirth Connect
+  tagline: An open source fork of the now closed-source Mirth® Connect
   image:
     src: 'https://raw.githubusercontent.com/OpenIntegrationEngine/governance/refs/heads/main/branding/logos/oie_logo_only.svg'
     alt: Open Integration Engine