Create contributions.md

add ./contributions.md file which has steps to help first time contributors to the project and also on code.swecha.org

• should address creating personal access tokens for the first time refer sample below

• NOTE: Make sure you set expiry date as per your convinence, else default date would be set for 4 weeks from the current date.

This Token is for authentication to the platform.

• Navigate to this page and create a token with the expiry date. Please save the token for further use.
• Navigate to the main branch to access the url from the clone button.
• Give clone URL, with placeholder for personal access token as shown in here
• Paste the copied token in your system directory with the command git clone url
• Token should be copied and saved for future usage. If lost, new token can be generated.
• After this step, you should find all the code that is cloned into your system directory.