Update github.com git repo URLs with framagit.org URLs

doc/context/en/admin/plugins/help.html

@@ -6,7 +6,7 @@
 		which opens a control panel for managing what plugin <i>repositories</i> are installed. These repos are 
 		stored in <span style="font-family: monospace;">extend/addon/[repo name]/</span>. The official Hubzilla 
 		plugin repo can be added by entering the repo URL
-		<span style="font-family: monospace;">https://github.com/redmatrix/hubzilla-addons.git</span>
+		<span style="font-family: monospace;">https://framagit.org/hubzilla/addons.git</span>
 		and choosing a name for the repo such as <b>official</b>. You should see this repo in the list similar 
 		to the following:
 		<br>