add remaining documentation

Author: András Kurai

.vscode/spellright.dict

@@ -0,0 +1,2 @@
+unrecoverably
+parameterless

Documentation/api/index.md

@@ -1,2 +1 @@
-# PLACEHOLDER
-TODO: Add .NET projects to the *src* folder and run `docfx` to generate **REAL** *API Documentation*!
+# C# API Documentation

Documentation/articles/Customization.md

@@ -3,3 +3,46 @@
 After pressing the `Generate Resource Paths` button, or visiting the `ResourceGenerator` page in the Project Settings an asset will be generated in the Assets folder, which will contain settings for the code generation.
 
 ## Built-in settings
+
+![Generate Button](~/images/Customization/DefaultSettings.png)
+
+### Basic settings
+
+- **Folder from Assets**: Relative path to the folder where you want the generated class
+- **Namespace**: The namespace of the generated class
+- **Class name**: The name of the generated class. The file name will be the same
+- **Log Infos**: Whether to log Info level logs. Turned off by default
+- **Log Errors**: Whether to log Error level logs. Turned on by default
+
+### Advanced settings
+
+> [!NOTE]
+> If you unrecoverably mess up your settings press the `Reset file mappings` button to restore the default file mappings
+
+The data section describes the automatically generated file mappings. The data is an array. For each element of the array it will create a new inner class of the main generated one.
+
+- **Class Name**: The name of the generated class
+- **File Extensions**: Search pattern for the files
+- **Data Type**: The C# type returned by `Resurces.Load`
+
+The default mappings are created from the [Unity documentation](https://docs.unity3d.com/Manual/BuiltInImporters.html). If you know of any valid file mapping that the documentation does not state, please fork and create a Pull Request, or create an [Issue](https://github.com/AutSoft/UnityResourceGenerator/issues/new).
+
+## Extending the generated classes
+
+The generated classes are `partial` by default. This means that if you want to add custom methods, simply create another `partial` class and add your code there.
+
+```csharp
+public static partial class ResourcePaths
+{
+    public static partial class Scenes
+    {
+        public static string[] MainScenes { get; } = new []
+        {
+            Coins,
+            Level1,
+            Level2,
+            // ...
+        }
+    }
+}
+```

Documentation/articles/Extensibility.md

@@ -0,0 +1,13 @@
+# Extensibility
+
+The library lets you to inject code into the generation pipeline. To access this feature, create a new Editor project, and reference `AutSoft.UnityResourceGenerator.Editor`. The included functionality is implemented using these mehtods.
+
+## Module generation
+
+A module is single string that is placed inside the main generated class. To create a custom module implement the [IModuleGenerator](xref:AutSoft.UnityResourceGenerator.Editor.Generation.IModuleGenerator) interface. The implementation must provide a parameterless constructor.
+
+## Post processing
+
+A post processor is a piece of code that is run after all modules are produced, and the final file text is created. To create a post processor implement the [IResourcePostProcessor](xref:AutSoft.UnityResourceGenerator.Editor.Generation.IResourcePostProcessor) interface. The implementation must provide a parameterless constructor.
+
+The input of the processor is the current state of the generated file and it returns the new state of the generated file. Post processors also provide a Priority property which determines the ordering of them.

Documentation/articles/toc.yml

@@ -2,3 +2,5 @@
   href: GettingStarted.md
 - name: Customization
   href: Customization.md
+- name: Extensibility
+  href: Extensibility.md