Merge pull request #13276 from JanneKiiskila/master-license-fat

MASTER - LICENSE.md - clarify filesystem licensing

Author: 0xc0170

LICENSE.md

@@ -17,7 +17,9 @@ Folders containing files under different permissive license than Apache 2.0 are
 - [features/netsocket/emac-drivers](./features/netsocket/emac-drivers) - BSD-style
 - [features/frameworks/unity/unity](./features/frameworks/unity/unity) - MIT
 - [features/unsupported](./features/unsupported) - MIT-style, BSD-style
-- [storage](./storage) - BSD-style, MIT
+- [storage/blockdevice](./storage/blockdevice) - Apache 2.0, MIT
+- [storage/filesystem/littlefs](.storage/filesystem/littlefs) - [BSD-3-Clause](https://github.com/ARMmbed/littlefs/blob/master/LICENSE.md)
+- [storage/filesystem/fat/ChaN](.storage/filesystem/fat/ChaN) - BSD-style, 1 clause, [Copyright ChaN](http://www.elm-chan.org/fsw/ff/doc/appnote.html)
 - [rtos](./rtos) - MIT
 - [drivers](./drivers) - MIT
 - [TESTS/mbed_hal/trng/pithy](./TESTS/mbed_hal/trng/pithy) - BSD-3-Clause