wiki: Document backdrop-color and overview-open-close animation

wiki/Configuration:-Animations.md

@@ -50,6 +50,10 @@ animations {
         duration-ms 200
         curve "ease-out-quad"
     }
+
+    overview-open-close {
+        spring damping-ratio=1.0 stiffness=800 epsilon=0.0001
+    }
 }
 ```
 
@@ -374,6 +378,20 @@ animations {
 }
 ```
 
+#### `overview-open-close`
+
+<sup>Since: next release</sup>
+
+The open/close zoom animation of the [Overview](./Overview.md).
+
+```kdl
+animations {
+    overview-open-close {
+        spring damping-ratio=1.0 stiffness=800 epsilon=0.0001
+    }
+}
+```
+
 ### Synchronized Animations
 
 <sup>Since: 0.1.5</sup>

wiki/Configuration:-Outputs.md

@@ -15,6 +15,7 @@ output "eDP-1" {
     variable-refresh-rate // on-demand=true
     focus-at-startup
     background-color "#003300"
+    backdrop-color "#001100"
 }
 
 output "HDMI-A-1" {
@@ -191,7 +192,7 @@ output "DP-2" {
 
 <sup>Since: 0.1.8</sup>
 
-Set the background color that niri draws for this output.
+Set the background color that niri draws for workspaces on this output.
 This is visible when you're not using any background tools like swaybg.
 
 The alpha channel for this color will be ignored.
@@ -201,3 +202,18 @@ output "HDMI-A-1" {
     background-color "#003300"
 }
 ```
+
+### `backdrop-color`
+
+<sup>Since: next release</sup>
+
+Set the backdrop color that niri draws for this output.
+This is visible between workspaces or in the overview.
+
+The alpha channel for this color will be ignored.
+
+```kdl
+output "HDMI-A-1" {
+    backdrop-color "#001100"
+}
+```