docs: add rustdoc comments to all module options

This part of an upcoming effort to generate documentation from code.

Pushing this out before that stage so that the JSON schema is fully documented.

src/modules/notifications.rs

@@ -11,28 +11,60 @@ use tracing::error;
 
 #[derive(Debug, Deserialize, Clone)]
 pub struct NotificationsModule {
+    /// Whether to show the current notification count.
+    ///
+    /// **Default**: `true`
     #[serde(default = "crate::config::default_true")]
     show_count: bool,
 
+    /// SwayNC state icons.
+    ///
+    /// See [icons](#icons).
     #[serde(default)]
     icons: Icons,
 
+    /// See [common options](module-level-options#common-options).
     #[serde(flatten)]
     pub common: Option<CommonConfig>,
 }
 
 #[derive(Debug, Deserialize, Clone)]
 struct Icons {
+    /// Icon to show when the panel is closed, with no notifications.
+    ///
+    /// **Default**: `󰍥`
     #[serde(default = "default_icon_closed_none")]
     closed_none: String,
+
+    /// Icon to show when the panel is closed, with notifications.
+    ///
+    /// **Default**: `󱥂`
     #[serde(default = "default_icon_closed_some")]
     closed_some: String,
+
+    /// Icon to show when the panel is closed, with DnD enabled.
+    /// Takes higher priority than count-based icons.
+    ///
+    /// **Default**: `󱅯`
     #[serde(default = "default_icon_closed_dnd")]
     closed_dnd: String,
+
+    /// Icon to show when the panel is open, with no notifications.
+    ///
+    /// **Default**: `󰍡`
     #[serde(default = "default_icon_open_none")]
     open_none: String,
+
+    /// Icon to show when the panel is open, with notifications.
+    ///
+    /// **Default**: `󱥁`
     #[serde(default = "default_icon_open_some")]
     open_some: String,
+
+    /// Icon to show when the panel is open, with DnD enabled.
+    /// Takes higher priority than count-based icons.
+    ///
+    /// **Default**: `󱅮`
     #[serde(default = "default_icon_open_dnd")]
     open_dnd: String,
 }