website: mark RT 1-yr warranty as optional on Purchase page

Author: gunyarakun

website/docs/purchase/index.mdx

@@ -104,7 +104,7 @@ Official Manufacturing Partners and Certified Manufacturers work closely with th
         </div>
         <div>
           <div style={{ color: '#6b7280' }}>🛠️ Includes</div>
-          <div style={{ fontWeight: '600' }}>Setup & testing, 1-yr warranty, JP-spec AC adapter</div>
+          <div style={{ fontWeight: '600' }}>Setup & testing, JP-spec AC adapter, optional 1-yr warranty</div>
         </div>
         <div>
           <div style={{ color: '#6b7280' }}>🌏 Shipping Regions</div>
@@ -120,7 +120,7 @@ Official Manufacturing Partners and Certified Manufacturers work closely with th
     }}>
       <strong>From the Supplier:</strong>
       <div style={{ marginTop: '0.5rem' }}>
-        As Enactic's official supplier in Japan, RT Corporation delivers OpenArm with local, Japanese-language support, drawing on over 20 years of humanoid robot development. Units arrive set up and tested, with a Japan-spec AC adapter, a 1-year warranty, and optional paid maintenance.
+        As Enactic's official supplier in Japan, RT Corporation delivers OpenArm with local, Japanese-language support, drawing on over 20 years of humanoid robot development. Units arrive set up and tested, with a Japan-spec AC adapter, plus an optional 1-year warranty and paid maintenance.
       </div>
       <strong>Available configurations:</strong>
       <div style={{ marginTop: '0.5rem' }}>