Document plugin icons (#390)

content/docs/10.plugin-developer-guide/08.documentation.md

@@ -1,7 +1,6 @@
 ---
 title: Document your plugin
 ---
-#
 
 First, let us remember the organization of a plugin project:
 
@@ -58,6 +57,10 @@ For example, for the GCP group of plugins, the file is `src/main/resources/doc/i
 
 If there are files inside the `src/main/resources/doc/guides` directory, we will list them in a `Guides` section on the documentation for the group of plugins.
 
+### Group Icon
+
+It is possible to provide an icon representing the whole plugin group. If there is a [SVG file](https://www.w3.org/Graphics/SVG/) `src/main/resources/icons/plugin-icon.svg`, it will be used as the group icon.
+
 ## Document the plugin sub-groups
 
 Each sub-group can be documented via the `io.kestra.core.models.annotations.PluginSubGroup` annotation that must be defined at the package level in a `package-info.java` file.
@@ -82,6 +85,12 @@ package io.kestra.plugin.gcp.bigquery;
 import io.kestra.core.models.annotations.PluginSubGroup;
 ```
 
+### Sub-Group Icon
+
+Each plugin sub-group can define an icon representing plugins contained in the sub-group. If there is a SVG file `src/main/resources/icons/<plugin-sub-group>.svg`, it will be used as the icon for the corresponding plugins.
+
+For example, for the GCP BigQuery sub-group, the `src/main/resources/icons/io.kestra.plugin.gcp.bigquery.svg` file is used.
+
 ## Document each plugin
 
 Plugin documentation will generate a [JSON Schema](https://json-schema.org/) that will be used to validate flows. It also generates documentation for both the UI and the website (see the `kestra plugins doc` command).