Add nagaba-phionah as contributor

[nagaba-phionah]

i have added my destails in CONTRIBUTORS.yaml

i have added my github userName followed by my name, country, email, gitter username and the month and year i joined.
and am currently a vice president at school of computing and Informatic Technology in Makerere University. i would like contribute on improving the on-boarding process to welcome and support new communities that show interest in joining Galaxy
and strengthen the contribution of communities that have recently joined the Galaxy Project.

[hexylena]

Hi @nagaba-phionah Welcome to the GTN! Being on the contributor list is not a pre-requisite to contributing to the GTN.

So we do not add people to the contributor list until their first contribution to avoid inaccurately increasing our statistics. We will leave this pull request open until you make your first contribution and merge it then :)

If you are looking for ideas of how to contribute here, please take a look at this issue with contribution ideas, or have a chat with us on Gitter/Matrix :)