add more details in README file

README.md

-## Installing dependencies
+# Branch "docs" - Project shiny-k8s
+
+## Definition
+
+For Developer, this branch is dedicated to write the complete documentation under sphinx (available on https://hub.pages.pasteur.fr/shiny-k8s/)
+
+Dear User, who develop Shiny application, please go to the dedicated project [shiny-k8s-example](https://gitlab.pasteur.fr/hub/shiny-k8s-example) containing example of using the components developped here. Please follow detailed instructions in the [User Guide](https://hub.pages.pasteur.fr/shiny-k8s/user_guide/index.html)
+
+## How to use
+
+### Installing dependencies
+
 ```sh
 sudo apt-get install graphviz graphviz-dev # needed for pygrahviz
 virtualenv .venv -p python3
@@ -6,7 +17,30 @@ source .venv/bin/activate
 pip install -r requirements.txt
 ```
 
-## See changes locally
+### See changes locally
+
 ```sh
 sphinx-autobuild source/ build/html --port 8044
 ```
+
+## Project Goal
+
+To help members of Bioinformatic & Biostatistic Hub and Institut Pasteur to correctly and easily deploy a web application, developed in Shiny ( with R or Python), under a Kubernetes cluster managed by the IT department, we have developed the shiny-k8s-toolkit using gitlab projects containig all the components to be used by user or developper to deploy their application.
+
+Dear User, who develop Shiny application, please go to the dedicated project [shiny-k8s-example](https://gitlab.pasteur.fr/hub/shiny-k8s-example) containing example of using the components developped here. Please follow detailed instructions in the [User Guide](https://hub.pages.pasteur.fr/shiny-k8s/user_guide/index.html)
+
+Dear Developer,you can stay here if you want to know how the shiny-k8s-toolkit is built. More information for developer in the [Developer Guide](https://hub.pages.pasteur.fr/shiny-k8s/developer_guide/index.html)
+
+## Project Structure
+
+This project use orphan branch concept [^1] to manage the different ressources using according to the usage.
+
+```ini
+shiny-k8s
+  ├── main
+  ├── helm              ### Dedicated Orphan branch to store helm template and help to manage the kubernetes configuration
+  ├── docker-images     ### Dedicated orphan branch to build docker images will be used in examples
+  └── docs              ### Dedicated orphan branch to host the sphinx documentation of toolkit
+```
+
+[^1]: [git definition](https://git-scm.com/docs/git-checkout/2.14.6#Documentation/git-checkout.txt---orphanltnewbranchgt)