add contributor: Serkan Holat for sharing OS video on LI

[reshamas]

@all-contributors please add @coni2k for sharing the video on open source on LinkedIn.

Ref: https://www.linkedin.com/posts/serkanholat_97-a-briefer-history-of-open-source-juan-activity-7184520274648719361-ZY98?utm_source=share&utm_medium=member_desktop