Adding a step by step instructions for contributing

CONTRIBUTING.md

@@ -12,3 +12,39 @@ You are welcome to propose and discuss enhancements using project [issues](https
 We recommend enabling [travis-ci](https://travis-ci.org/) and [AppVeyor](https://www.appveyor.com/) on your fork of `librealsense` to make sure the changes compile on all platforms and pass unit-tests.
 
 Please familirize yourself with the [Apache License 2.0](https://github.com/IntelRealSense/librealsense/blob/master/LICENSE) before contributing. 
+
+## Step-by-Step
+
+1. Make sure you have `git` and `cmake` installed on your system. On Windows we recommend using [Git Extensions](https://github.com/gitextensions/gitextensions/releases) for git bash. 
+2. Run `git clone https://github.com/IntelRealSense/librealsense.git` and `cd librealsense`
+3. To align with latest status of the development branch, run:
+```
+git fetch origin
+git checkout development
+git reset --hard origin/development
+```
+4. `git checkout -b name_of_your_contribution` to create a dedicated branch
+5. Make your changes to the local repository
+6. Make sure your local git user is updated, or run `git config --global user.email "[email protected]"` and `git config --global user.user "user"` to set it up. This is the user & email that will appear in GitHub history. 
+7. `git add -p` to select the changes you wish to add
+8. `git commit -m "Description of the change"`
+9. Make sure you have a GitHub user and [fork librealsense](https://github.com/IntelRealSense/librealsense#fork-destination-box)
+10. `git remote add fork https://github.com/username/librealsense.git` with your GitHub `username`
+11. `git fetch fork`
+12. `git push fork` to push `name_of_your_contribution` branch to your fork
+13. Go to your fork on GitHub at `https://github.com/username/librealsense`
+14. Click the `New pull request` button
+15. For `base` combo-box select `development`, since you want to submit a PR to that branch
+16. For `compare` combo-box select `name_of_your_contribution` with your commit
+17. Review your changes and click `Create pull request`
+18. Wait for all automated checks to pass
+19. The PR will be approved / rejected after review from the team and the community
+
+To continue to new change, goto step 3.
+To return to your PR (in order to make more changes):
+1. `git stash`
+2. `git checkout name_of_your_contribution`
+3. Repeat items 5-8 from the previous list
+4. `git push fork`
+The pull request will be automatically updated
+