Add battle-tested production statement to documentation (#62)

* Initial plan

* Add battle-tested production statement to README and docs

Co-authored-by: hckhanh <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: hckhanh <[email protected]>

Author: Copilot

README.md

@@ -15,6 +15,7 @@
 - Fully documented
 - Works with `number`, `string`, and `bigint` types
 - Handles very large numbers (up to quintillions)
+- Battle-tested in production apps and dashboards
 
 ## Installation
 

docs/content/docs/index.mdx

@@ -218,6 +218,11 @@ console.log(`Tăng trưởng: ${formatVnPercent(growthRate)}`);
   API for formatting operations.
 </Callout>
 
+<Callout title="Battle-Tested in Production" type="info">
+  This library is battle-tested in production apps and dashboards, providing
+  reliable number formatting and reading for Vietnamese language applications.
+</Callout>
+
 ## Next Steps
 
 <Cards>