milestone 21: abp list exceptions and a regex rule kind

src/filter/wildcard.zig

@@ -4,7 +4,8 @@
 //! A pattern is a domain name in which one or more labels are exactly `*`.
 //! Each `*` label matches one or more labels of the queried name. Partial-label
 //! globbing (`ad*.example.com`) is deliberately absent: it is regex by another
-//! name, which PLAN §2.2 rules out.
+//! name, and PLAN §2.2 keeps one regex dialect rather than two. An operator who
+//! needs one writes a `.regex` rule, which `filter/regex.zig` compiles.
 
 const std = @import("std");
 
@@ -18,8 +19,9 @@ pub const PatternError = error{
     /// No label is exactly "*".
     NoWildcard,
     /// A label contains '*' but is not exactly "*". Partial-label globbing
-    /// (`ad*.example.com`) is out of scope: it is regex by another name, and
-    /// PLAN §3.9 defines the wildcard as a label pattern.
+    /// (`ad*.example.com`) is out of scope: PLAN §3.9 defines the wildcard as a
+    /// label pattern, and the `.regex` kind covers what partial globbing was
+    /// wanted for.
     PartialWildcardLabel,
     EmptyLabel,
     LabelTooLong,