doc: yambar-modules: document the river module

Closes #9

CHANGELOG.md

@@ -10,6 +10,8 @@
 * alsa: `percent` tag. This is an integer tag that represents the
   current volume as a percentage value
   (https://codeberg.org/dnkl/yambar/issues/10).
+* river: added documentation
+  (https://codeberg.org/dnkl/yambar/issues/9).
 
 
 ### Deprecated

doc/yambar-modules.5.scd

@@ -641,6 +641,81 @@ bar:
                   deco: {underline: {size: 2, color: ffffffff}}
 ```
 
+# RIVER
+
+This module uses river's (https://github.com/ifreund/river, a dynamic
+tiling Wayland compositor) status protocol to provide information
+about the river tags.
+
+It has an interface similar to the i3/sway module.
+
+The configuration for the river module speficies one _title_ particle,
+which will be instantiated with tags representing the currently active
+seat and the currently focused view's title.
+
+It also specifies a _content_ template particle, which is instantiated
+once for all 32 river tags. This means you probably want to use a
+*map* particle to hide unused river tags.
+
+## TAGS
+
+[[ *Name*
+:[ *Type*
+:[ *Description*
+|  id
+:  int
+:  River tag number
+|  visible
+:  bool
+:  True if the river tag is focused by at least one output (i.e. visible on at least one monitor).
+|  focused
+:  bool
+:  True if the river tag is _visible_ and has keyboard focus.
+|  occupied
+:  bool
+:  True if the river tag has views (i.e. windows).
+|  state
+:  string
+:  Set to *focused* if _focused_ is true, *unfocused* if _visible_ is true, but _focused_ is false, or *invisible* if the river tag is not visible on any monitors.
+|  seat
+:  string
+:  The name of the currently active seat (*title* particle only, see CONFIGURATION)
+|  title
+:  string
+:  The focused view's title (*title* particle only, see CONFIGURATION)
+
+## CONFIGURATION
+
+[[ *Name*
+:[ *Type*
+:[ *Req*
+:[ *Description*
+|  title
+:  particle
+:  no
+:  Particle that will be instantiated with the _seat_ and _title_ tags.
+|  content
+:  particle
+:  yes
+:  Template particle that will be instantiated once for all of the 32 river tags.
+
+## EXAMPLES
+
+```
+bar:
+  left:
+    - river:
+        title: {string: { text: "{seat} - {title}" }}
+        content:
+          map:
+            tag: occupied
+            values:
+              false: {empty: {}}
+              true:
+                string:
+                  margin: 5
+                  text: "{id}: {state}"```
+
 # SWAY-XKB
 
 This module uses *Sway* extenions to the I3 IPC API to monitor input