added contributing.md file

[onemriganka]

fixes / #101
HEY, I HAVE ADDED A SIMPLE CONTRIBUTING.MD FILE. HOPE IT WILL HELP BEGINEERS

[Fokko]

@onemriganka What do you think of pointing to https://py.iceberg.apache.org/contributing/? Otherwise we have to maintain this at two places

[onemriganka]

@onemriganka What do you think of pointing to https://py.iceberg.apache.org/contributing/? Otherwise we have to maintain this at two places

YES ,https://py.iceberg.apache.org/contributing/ <- this is great .But i think as begineers only find usefull files like README.md etc only in github. so when we have contributing.md file in the repo will be easy for begineer to understand and contribute. professionals check website of the project but many begineer do not

[Fokko]

But what are your thoughts on linking from the CONTRIBUTING.md to the website? Otherwise, it is abound to get out of sync.

[onemriganka]

OK sir, if you think the website is more helpful then ok... Thanks