Fix Markdown format in app description

Signed-off-by: Mostafa Ahangarha <ahangarha@riseup.net>

appinfo/info.xml

@@ -5,8 +5,7 @@
 	<name>Social</name>
 	<summary>🎉 Nextcloud becomes part of the federated social networks!</summary>
 	<description><![CDATA[
-
-	** Disclaimer: this is a BETA version **
+**Disclaimer: this is a BETA version**
 
 **🎉 Nextcloud becomes part of the federated social networks!**