Fix link in FATFileSystem.md

Replace link that points to both GitHub and teams at the same time.

Author: Amanda Butler

docs/api/storage/FATFileSystem.md

@@ -38,7 +38,7 @@ To configure this class, please see the [FileSystem configuration documentation]
 
 ### FATFileSystem example
 
-[![View code](https://www.mbed.com/embed/?url=https://github.com/armmbed/mbed-os-example-filesystem)](https://os.mbed.com/teams/mbed-os-examples/code/mbed-os-example-filesystem/file/54f958b463d0/main.cpp)
+[![View code](https://www.mbed.com/embed/?url=https://github.com/armmbed/mbed-os-example-filesystem/)](https://github.com/ARMmbed/mbed-os-example-filesystem/blob/master/main.cpp)
 
 ### Related content