[NRRPLT-6587] README file for externals

README.md

+This repository is part of the Neurorobotics Platform software
+Copyright (C) Human Brain Project
+https://neurorobotics.ai
+
+The Human Brain Project is a European Commission funded project
+in the frame of the [Horizon2020 FET Flagship plan](http://ec.europa.eu/programmes/horizon2020/en/h2020-section/fet-flagships).
+
+
+You are free to clone this repository and amend its code with respect to
+the license that you find in the root folder.
+
+## Submitting a pull request
+
+To submit code changes (pull requests) as a person external to the project, do as follows.
+
+0. Log in to Bitbucket
+1. Fork the project: "+" button, "Fork this repository".
+2. Clone the forked project (eg. ```git clone git@bitbucket.org:[USERNAME]/[REPOSITORY].git```)
+3. Create a branch. Give it an explicit name referring a ticket number in [Jira](https://hbpneurorobotics.atlassian.net)
+4. Do your code changes
+5. Commit your changes. 
+  **Make sure** your commit message starts with ```[<ticket_number>]```.
+   Example: "[NUIT-10] My new feature"
+6. ```git push```
+7. Click on the url provided on the console output for the previous command to create the pull request
+8. A core developer will eventually review your pull request and approve or comment it
+