about: adding XMPP to contact info

Author: ariadnavigo

content/about/index.md

@@ -24,3 +24,4 @@ These are the ways you can find me on the internet:
    (You may find my OpenPGP key via WKD) 
 2. **GitHub:** [@ariadnavigo](https://github.com/ariadnavigo)
 3. **Mastodon:** [@ariadna@social.tchncs.de](https://social.tchncs.de/@ariadna)
+4. **XMPP:** [[email protected]](xmpp:[email protected])