add description about files for the application

workspace/README.md

@@ -2,7 +2,7 @@
 
 This repository contains example applications for mros2-asp3-f767zi (mROS 2 with TOPPERS/ASP3 kernel).
 
-## Selecting the application
+## Selection of the application to build
 
 You can select the application to be built with `make` option.
 
@@ -25,3 +25,25 @@ $ make app=pub_float32
 
 We also provide the implemenation of ROS 2 nodes on the host, that communicate to the embedded device. 
 Please also check [mROS-base/mros2-host-examples](https://github.com/mROS-base/mros2-host-examples) repository for more details about corresponding example ROS 2 packages on the host.
+
+## Files for the application
+
+On this platform, the mros2 application consists of the following files:
+
+- app.cpp: 
+  - main source of the application
+  - note that the file name must be this in order to generate the templates of pub/sub functions in the build step.
+- app.h: 
+  - header file of the application
+  - some definitions for the configuration of TOPPERS/ASP3 kernel and its tasks
+- templates.hpp:
+  - the templates of pub/sub functions
+  - this file will be automatically generated/modified during the build step, so you do not have to care about this file
+- Makefile.inc: the definication of make for mros2 application
+- app.cfg: system configuration file for TOPPERS/ASP3 kernel
+- app.cdl: description of TECS components for TOPPERS/ASP3 kernel
+- task_impl.[c,h]: the definition of the wrapper for CMSIS layer
+- config/: the configuration of the wrapper for CMSIS layer
+
+You may warry these many files about the settings. 
+However, roughly speaking, just you need to do is to copy the existing directory and edit app.cpp to create a new application.