Update README.md (#1408)

* Update README.md

Updated README.md to include mention of semantic versioning. Addresses DRIVERS-3105.

* Update README.md

Co-authored-by: Ezra Chung <[email protected]>

---------

Co-authored-by: Ezra Chung <[email protected]>

Author: rishitb-mongodb

README.md

@@ -35,6 +35,8 @@ git clone -b releases/stable https://github.com/mongodb/mongo-cxx-driver.git
 | ...         | ...             | ...                         | ...                |
 | 3.0.0       | None            | Ready for Use               | Not Supported      |
 
+This project uses [Semantic Versioning](https://semver.org/).
+
 ## MongoDB Server Compatibility
 
 MongoDB server version compatibility per driver version is documented in the [MongoDB Manual](https://www.mongodb.com/docs/languages/cpp/cpp-driver/current/compatibility/).