Update Enonic XP github repo.

Changed from enonic/xp-distro to enonic/xp. The xp-distro repo is more
of a bundle, while the xp repo is the actual repo where work
happens. Thus, the xp repo is where to go to check out the source
code, stars, etc.

Author: Thomas Heartman

src/site/headless-cms/enonic-xp.md

@@ -1,6 +1,6 @@
 ---
 title: Enonic XP
-repo: enonic/xp-distro
+repo: enonic/xp
 homepage: https://enonic.com/
 twitter: EnonicHQ
 opensource: "Yes"