update example description

Author: hathach

examples/host/msc_file_explorer/src/main.c

@@ -23,6 +23,38 @@
  *
  */
 
+/* Example to show how to navigate mass storage device with built-in command line.
+ * Type help for list of supported commands and syntax (mostly linux commands)
+
+ > help
+ * help
+        Print list of commands
+ * cat
+        Usage: cat [FILE]...
+        Concatenate FILE(s) to standard output..
+ * cd
+        Usage: cd [DIR]...
+        Change the current directory to DIR.
+ * cp
+        Usage: cp SOURCE DEST
+        Copy SOURCE to DEST.
+ * ls
+        Usage: ls [DIR]...
+        List information about the FILEs (the current directory by default).
+ * pwd
+        Usage: pwd
+        Print the name of the current working directory.
+ * mkdir
+        Usage: mkdir DIR...
+        Create the DIRECTORY(ies), if they do not already exist..
+ * mv
+        Usage: mv SOURCE DEST...
+        Rename SOURCE to DEST.
+ * rm
+        Usage: rm [FILE]...
+        Remove (unlink) the FILE(s).
+ */
+
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>