feat: add docs

docs/extensibility/README.md

@@ -4,6 +4,8 @@
 
 With Busola's extensibility feature, you can create a dedicated user interface (UI) page for your CustomResourceDefinition (CRD). It enables you to add navigation nodes, on cluster or namespace level, and to configure your [UI display](./30-details-summary.md), for example, a resource list page, and details pages. You can also [create and edit forms](./40-form-fields.md). To create a UI component, you need a ConfigMap.
 
+You can also leverage Busola's [custom extension feature](./custom-extensions.md) to design entirely custom user interfaces tailored to your specific needs.
+
 ## Create a ConfigMap for Your UI
 
 To create a ConfigMap with your CRD's UI configuration, you can either use the Extensions feature or do it manually.

docs/extensibility/custom-extensions.md

@@ -0,0 +1,24 @@
+# Custom Extensions
+
+Busola's custom extension feature allows you to design fully custom user interfaces that go beyond the built-in extensibility functionality. This feature is ideal for creating unique and specialized displays that are not covered by the standard built-in components.
+
+## Getting Started
+
+First, to enable the custom extension feature you need to set the corresponding feature flag in your busola config, which is disabled by default.
+
+```yaml
+EXTENSIBILITY_CUSTOM_COMPONENTS:
+  isEnabled: true
+```
+
+## Creating custom extensions
+
+Creating a custom extension is as straightforward as setting up a ConfigMap with the following sections:
+
+- `data.general`: Contains configuration details
+- `data.customHtml`: Defines static HTML content
+- `data.customScript`: Adds dynamic behavior to your extension.
+
+Once your ConfigMap is ready, add it to your cluster, and Busola will load and display your custom UI.
+
+The best way to get familiar with this mechanism is to have a look at our [example](./../../examples/custom-extension/README.md), where everything is explained in detail.

docs/features.md

@@ -56,6 +56,15 @@ EXTENSIBILITY:
   isEnabled: true
 ```
 
+- **EXTENSIBILITY_CUSTOM_COMPONENTS** - is used to indicate whether entirely custom extensions can be added to Busola. An example for a custom extension can be found [here](../examples/web-component-ext/README.md).
+
+Default settings:
+
+```yaml
+EXTENSIBILITY_CUSTOM_COMPONENTS:
+  isEnabled: false
+```
+
 - **EXTERNAL_NODES** - a list of links to external websites. `category`: a category name, `icon`: an optional icon, `scope`: either `namespace` or `cluster` (defaults to `cluster`), `children`: a list of pairs (label and link).
 
   Default settings:

examples/custom-extension/README.md

@@ -1,6 +1,6 @@
 # Set Up Your Custom Busola Extension
 
-This example contains a basic custom extension, that queries all deployments corresponding to a selected namespace of your cluster, and additionally retrieves the current weather data for Munich, Germany from an external weather API.
+This example contains a basic custom extension, that queries all deployments of a selected namespace of your cluster, and additionally retrieves the current weather data for Munich, Germany from an external weather API.
 
 To set up and deploy your own custom Busola extension, follow these steps.