add some clarification about additional dirs, and expected license...

Also remind people that it's their responsiblity to follow licenses..

LICENSE.txt

@@ -1,6 +1,15 @@
 Files in the directory strobe are licensed by the terms specified
 in the directory.
 
+Files in the directory stm32 are licensed as labeled.
+
+Files in the directory loramac are licensed as labeled and/or per
+the LICENSE file in the directory.
+
+Most/all the third party files should be on a permission license
+such as BSD, MIT or Apache license.  As usual, it is your responsibility
+to ensure that you follow the terms of the licenses as stated.
+
 Remaining files are licensed under the following unless otherwise marked.
 
 Copyright 2021 John-Mark Gurney.