Fix Swagger example not using actual values for chains (#28)

Modify the hardcoded 'EOS' example to the array of `supportedChains`
for Swagger to detect the right value to use in the examples.

src/schemas.ts

@@ -59,7 +59,7 @@ export const BlockchainSchema = z.object({
             name: 'chain',
             in: 'path',
         },
-        example: 'EOS',
+        examples: supportedChains,
     })
 });