Add project layout docs

README.md

@@ -34,6 +34,7 @@ $ ./bin/server --config-file ./config-server.yml
 
 ## Docs
 - [System Design](./docs/design.md)
+- [Project Structure](./docs/project_structure.md)
 
 ## Contribution
 If you are interested in contributing to this project,

docs/project_structure.md

@@ -0,0 +1,18 @@
+## Project Structure
+This page describes how project layout is organized.
+
+```shell
+.
+├── cmd
+│    └── cosmscan : (main package)
+├── internel : (internal packages)
+│    ├── db : defines postgres database object
+│    ├── client : defines cosmos & tendermint client
+│    └── config : defines global configuration object
+├── proto : protobuf files are defined in here
+├── modules 
+│    ├── server : represents API server based on gRPC & HTTP protocol
+│    └── indexer : represents indexer engine 
+├── pkg : useful util functions are defined in here
+└── example : anyone can launch cosmscan with this example in local machine.
+```