Updated site config file template's default API

So as to match the change in Staticman's default API introduced in onweru#36.  Note
that onweru#36 is a breaking change. for users who have set Staticman `endpoint` to
the empty string "".  However, the official production instance has already
broken, as reported in eduardoboucas/staticman#307, so this commit is simply an
info update.

exampleSite/config.toml

@@ -17,7 +17,7 @@ pygmentsCodefencesGuessSyntax = true
   # twitter = "" # twitter handle e.g @weru
 
 # [params.staticman]
-#   endpoint = "https://api.staticman.net"  # URL of your own API deployment (without trailing slash), default: "https://api.staticman.net"
+#   endpoint = ""  # URL of your own API deployment (without trailing slash), default: "https://staticman-frama.herokuapp.com"
 #   gitProvider = "github"  # Either "github" or "gitlab"
 #   username = "username"  # GitHub/GitLab user name
 #   repository = "repo"  # GitHub/GitLab user name