Set title for home page in index.md

Otherwise, page title looks like : "(empty) - ejabberd Docs". 

See : https://github.com/squidfunk/mkdocs-material/blob/master/src/templates/base.html#L92

Author: Metalhearf

content/index.md

@@ -1,4 +1,4 @@
 ---
-title: " "
+title: "Home"
 template: home.html
 ---