Update README.md (#23760)

beautified Readme , removed bullet

README.md

diff --git a/README.md b/README.md
index 0c6095f..592ccd1 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@
 
 ### Documentation
 
-* **Main site: [flutter.io][]**
+**Main site: [flutter.io][]**
 * [Install](https://flutter.io/get-started/install/)
 * [Get started](https://flutter.io/get-started/)
 * [Changelog](https://github.com/flutter/flutter/wiki/Changelog)