Update EEP-59 to not allow multiple -doc entries

The implementation already works like this.

Author: garazdawi

eeps/eep-0059.md

@@ -92,20 +92,13 @@ is equivalent to:
     example() -> ok.
 
 Listing multiple `-doc` attributes with string values for the same
-function should warn or error accordingly, unless the documentation
-is being set to hidden. For example, this is valid:
-
-    -doc "Example".
-    -doc hidden.
-    example() -> ok.
-
-But this should warn/error:
+function should warn or error accordingly. The examples below should error:
 
     -doc "Example".
     -doc "Updated example".
     example() -> ok.
 
-This as well:
+<!-- split examples -->
 
     -doc "Example".
     example(one) -> 1;