update doc to not use the root zone for everything (#3288)

Update all documentation in the tree to use example.org as an example
configuration (in so far possible). As to get out of the just use "."
and fallthrough and things would be fine.

Signed-off-by: Miek Gieben <miek@miek.nl>

plugin/errors/README.md

@@ -38,10 +38,10 @@ For better performance, it's recommended to use the `^` or `$` metacharacters in
 
 ## Examples
 
-Use the *whoami* to respond to queries and Log errors to standard output.
+Use the *whoami* to respond to queries in the example.org domain and Log errors to standard output.
 
 ~~~ corefile
-. {
+example.org {
     whoami
     errors
 }