Use better syntax for doc comment attribute

As per
  https://gitlab.torproject.org/tpo/core/arti/-/merge_requests/471#note_2798020

crates/arti/src/logging.rs

@@ -66,9 +66,7 @@ impl LoggingConfig {
 type LogfileListConfig = Vec<LogfileConfig>;
 
 define_list_config_builder! {
-    [
     /// List of logfiles to use, being built as part of the configuration
-    ]
     pub struct LogfileListConfigBuilder {
         files: [LogfileConfigBuilder],
     }

crates/tor-circmgr/src/config.rs

@@ -186,9 +186,7 @@ fn default_preemptive_threshold() -> usize {
 type PredictedPortsList = Vec<u16>;
 
 define_list_config_builder! {
-    [
     /// List of preemptive ports, being built as part of the configuration
-    ]
     pub struct PredictedPortsListBuilder {
         pub(crate) ports: [u16],
     }

crates/tor-config/src/list_builder.rs

@@ -35,9 +35,7 @@
 /// pub struct ThingList { things: Vec<Thing> }
 ///
 /// define_list_config_builder! {
-///    [
 ///    /// List of things, being built as part of the configuration
-///    ]
 ///    pub struct ThingListBuilder {
 ///        pub(crate) things: [ThingBuilder],
 ///    }
@@ -55,9 +53,7 @@
 #[macro_export]
 macro_rules! define_list_config_builder {
     {
-        [
-            $($docs_and_attrs:tt)*
-        ]
+        $(#[ $docs_and_attrs:meta ])*
         pub struct $ListBuilder:ident {
             $field_vis:vis $things:ident : [$EntryBuilder:ty] $(,)?
         }
@@ -65,7 +61,7 @@ macro_rules! define_list_config_builder {
         default = $default:expr;
         $( item_build: $item_build:expr; )?
     } => {
-        $($docs_and_attrs)*
+        $(#[ $docs_and_attrs ])*
         #[derive(Default, Clone, Deserialize)]
         #[serde(transparent)]
         ///

crates/tor-dirmgr/src/authority.rs

@@ -45,9 +45,7 @@ impl Authority {
 pub(crate) type AuthorityList = Vec<Authority>;
 
 define_list_config_builder! {
-    [
     /// List of authorities, being built as part of the configuration
-    ]
     pub struct AuthorityListBuilder {
         authorities: [AuthorityBuilder],
     }

crates/tor-guardmgr/src/fallback/set.rs

@@ -31,13 +31,11 @@ impl<T: IntoIterator<Item = FallbackDir>> From<T> for FallbackList {
 }
 
 define_list_config_builder! {
-    [
     /// List of fallback directories, being built as part of the configuration
     ///
     /// Fallback directories (represented by [`FallbackDir`]) are used by Tor
     /// clients when they don't already have enough other directory information to
     /// contact the network.
-    ]
     pub struct FallbackListBuilder {
         pub(crate) fallbacks: [FallbackDirBuilder],
     }