Add section for new contributors
Add section for new contributors

Inspiration from this blog post: https://manishearth.github.io/blog/2016/01/03/making-your-open-source-project-newcomer-friendly/

Some parts are lifted from: https://github.com/servo/servo/blob/master/CONTRIBUTING.md

Signed-off-by: Goutham Veeramachaneni <caf616f34019d2c106581c18639c41d1bae35076@iith.ac.in>

kangwoo/prometheus,JavierZunzunegui/prometheus,alileza/prometheus,keegancsmith/prometheus,Conorbro/prometheus,AlekSi/prometheus,brancz/prometheus,amorken/prometheus,kangwoo/prometheus,Conorbro/prometheus,JavierZunzunegui/prometheus,JavierZunzunegui/prometheus,prometheus/prometheus,Stackdriver/stackdriver-prometheus,alileza/prometheus,AlekSi/prometheus,AlekSi/prometheus,Gouthamve/prometheus,keegancsmith/prometheus,Colstuwjx/prometheus,brancz/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,keegancsmith/prometheus,amorken/prometheus,Gouthamve/prometheus,prometheus/prometheus,prometheus/prometheus,kangwoo/prometheus,GoogleCloudPlatform/prometheus,amorken/prometheus,yanghongkjxy/prometheus,Gouthamve/prometheus,Stackdriver/stackdriver-prometheus,alileza/prometheus,Conorbro/prometheus,brancz/prometheus,Stackdriver/stackdriver-prometheus,keegancsmith/prometheus,amorken/prometheus,alileza/prometheus,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,Colstuwjx/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,yanghongkjxy/prometheus,AlekSi/prometheus,yanghongkjxy/prometheus,Colstuwjx/prometheus,alileza/prometheus,JavierZunzunegui/prometheus,kangwoo/prometheus,Colstuwjx/prometheus,Stackdriver/stackdriver-prometheus,Gouthamve/prometheus,yanghongkjxy/prometheus,brancz/prometheus,Conorbro/prometheus,keegancsmith/prometheus