Write out CalVer

Author: hynek

.github/SECURITY.md

@@ -2,7 +2,7 @@
 
 ## Supported Versions
 
-We are following [*CalVer*](https://calver.org) with generous backwards-compatibility guarantees.
+We are following [Calendar Versioning](https://calver.org) with generous backwards-compatibility guarantees.
 Therefore we only support the latest version.
 
 Put simply, you shouldn't ever be afraid to upgrade as long as you're only using our public APIs.