doc: add workspace and project structure information

README.md

@@ -6,9 +6,19 @@ A Rust EAV data model implementation
 
 Learn more on EAV data model [here](https://en.wikipedia.org/wiki/Entity%E2%80%93attribute%E2%80%93value_model).
 
-## Project Structure
+## Workspace Structure
 
-...
+- **01.workspace**: this folder contains all workspace crates
+
+## heave crate structure
+
+- **src/fun**: contains all functions
+- **src/imp**: contains all implementation (impl blocks)
+- **src/mcr**: contains all macros
+- **src/str**: contains all structures
+- **src/trt**: contains all traits
+- **src/tst**: contains all tests
+- **lib.rs**: renames and re-exports code compnents
 
 ## Example