add docs for molock

docs/docs/behaviors/layers.md

@@ -149,6 +149,43 @@ Example:
 
 It is possible to use "toggle layer" to have keys that raise and lower the layers as well.
 
+## Momentary Layer Lock
+
+Even if you mostly use momentary layers, it's occasionally useful to permanently enable a layer without needing to hold anything down. Instead of creating a separate `&tog` or `&to` binding for each layer, you can use `&molock`.
+
+`&molock` causes all currently active momentary layers not to be deactivated when `&mo` is released. If no momentary layers are active, `&molock` triggers a fallback behavior, which by default returns to the base layer (`&to 0`), deactivating any locked momentary layers in the process. Alternatively, the user can deactivate a single locked momentary layer by pressing and releasing the corresponding `&mo` binding again.
+
+### Behavior Binding
+
+- Reference: `&molock`
+
+Example:
+
+```dts
+&molock
+```
+
+### Configuration
+
+You can configure a different fallback behavior by overriding the `bindings` property of the built-in `&molock` behavior. For example, to return to layer 1 (instead of layer 0):
+
+```dts
+&molock {
+    bindings = <&to 1>;
+};
+```
+
+You can also create any number of custom `&molock` behaviors by using `compatible = "zmk,behavior-momentary-layer-lock"` like so:
+
+```dts
+// Presses F if triggered while no momentary layers are active
+kp_molock: kp_molock {
+    compatible = "zmk,behavior-momentary-layer-lock";
+    label = "KP_MOLOCK";
+    bindings = <&kp F>;
+};
+```
+
 ## Conditional Layers
 
 The "conditional layers" feature enables a particular layer when all layers in a specified set are active.

docs/docs/config/behaviors.md

@@ -210,6 +210,30 @@ Definition files:
 
 With `compatible = "zmk,behavior-sensor-rotate-var"`, this behavior forwards the first parameter it receives to the parameter of the first behavior specified in `bindings`, and second parameter to the parameter of the second behavior.
 
+## Momentary Layer Lock
+
+Creates a custom behavior that locks any active momentary layers or—if none are active—triggers the fallback behavior specified in `bindings`.
+
+See the [momentary layer lock](../behaviors/layers.md#momentary-layer-lock) documentation for more details and examples.
+
+### Devicetree
+
+Definition file: [zmk/app/dts/bindings/behaviors/zmk,behavior-momentary-layer-lock.yaml](https://github.com/zmkfirmware/zmk/blob/main/app/dts/bindings/behaviors/zmk%2Cbehavior-momentary-layer-lock.yaml)
+
+Applies to: `compatible = "zmk,behavior-momentary-layer-lock"`
+
+| Property         | Type          | Description                                             |
+| ---------------- | ------------- | ------------------------------------------------------- |
+| `label`          | string        | Unique label for the node                               |
+| `#binding-cells` | int           | Must be `0`                                             |
+| `bindings`       | phandle array | A behavior to trigger if no momentary layers are active |
+
+You can use the following nodes to tweak the default behaviors:
+
+| Node      | Behavior                                                            |
+| --------- | ------------------------------------------------------------------- |
+| `&molock` | [Momentary Layer Lock](../behaviors/layers.md#momentary-layer-lock) |
+
 ## Sticky Key
 
 Creates a custom behavior that triggers a behavior and keeps it pressed it until another key is pressed and released.