Adding mbed FW version and release notes

Revision:
56:2291d31c0bb9
Parent:
55:38b36e947602
--- a/mbed_release.txt	Mon Feb 24 08:49:25 2020 +0000
+++ b/mbed_release.txt	Tue Feb 25 05:34:20 2020 +0000
@@ -1,5 +1,5 @@
 ================================================================================
-=                            Mbed Host Firmware                                 =
+=                            Mbed Host Firmware                                =
 =                                                                              =
 =                              Release notes                                   =
 ================================================================================