Update README.md
Created by: chenejac
What does this pull request do?
This PR is updating readme file. The section for joining/contacting the community, as well as section for contributing is updated.
What's new?
README.md file is updated.
How should this be tested?
There is no testing by running application, just open README.md file at the root of the project and check whether text is clear and whether links are not broken.
Interested parties
Tag (@ mention) interested parties or, if unsure, @VIVO-project/vivo-committers