docs/Clients.md: Add Social (GNOME)

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docs/Clients.md

@@ -14,6 +14,12 @@ Feel free to contact us to be added to this list!
 - Contact: [@h3poteto@pleroma.io](https://pleroma.io/users/h3poteto)
 - Platforms: Windows, Mac, Linux
 
+### Social
+- Source Code: <https://gitlab.gnome.org/BrainBlasted/Social>
+- Contact: [@brainblasted@social.libre.fi](https://social.libre.fi/users/brainblasted)
+- Platforms: Linux (GNOME)
+- Note(2019-01-28): Not at a pre-alpha stage yet
+
 ## Handheld
 ### Roma
 - Homepage: <http://www.pleroma.com/>