Add some documentation.

plugins/src/main/java/io.element.android-compose-application.gradle.kts

@@ -1,3 +1,6 @@
+/**
+ * This will generate the plugin "io.element.android-compose-application", used only in the module `app`.
+ */
 import extension.androidConfig
 import extension.commonDependencies
 import extension.composeConfig

plugins/src/main/java/io.element.android-compose-library.gradle.kts

@@ -1,3 +1,6 @@
+/**
+ * This will generate the plugin "io.element.android-compose-library", used in android library with compose modules.
+ */
 import extension.androidConfig
 import extension.commonDependencies
 import extension.composeConfig

plugins/src/main/java/io.element.android-library.gradle.kts

@@ -1,3 +1,6 @@
+/**
+ * This will generate the plugin "io.element.android-library", used in android library without compose modules.
+ */
 import extension.androidConfig
 import extension.commonDependencies