Update description of mirror pool configuration.

wiki/src/blueprint/HTTP_mirror_pool.mdwn

@@ -95,6 +95,11 @@ of them we need a few values:
    0 means that the mirror is currently disabled, and will never be
    redirected to
 
+ * email (optional): the email address of the mirror's operator
+
+ * notes (optional): various additional notes that can be useful to
+   the managers of the mirror pool
+
 For a more formal, and probably more up-to-date definition of the data
 model, better see
 [its JSON schema](https://git-tails.immerda.ch/mirror-pool/tree/schema.json).
@@ -102,14 +107,6 @@ model, better see
 Here is
 [an example configuration file](https://git-tails.immerda.ch/mirror-pool/tree/example-mirrors.json).
 
-Later, we may want to add more data that is not blocking for the
-initial iterations:
-
- * email: contact information for the operator(s) of this mirror; XXX:
-   check if all mirror operators are OK with this; if enough are OK,
-   then document on [[contribute/how/mirror]] that it's the case, and
-   do it; otherwise, we'll need to manage contact info separately.
-
 # Initial research
 
 See [[HTTP_mirror_pool/archive]].