docs: Wiki page for File Structure and document app data option

CHANGELOG.md

@@ -8,6 +8,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- New `--app-data` option for overriding the location of the application data directory.
+
 ### Fixed
 
 - Version information in help output has been fixed.

wiki/Command-Line-Reference.md

@@ -91,6 +91,12 @@ By default, Info, Warning and Error log levels are displayed in the console. Thi
 Debug level logs to be displayed. This is designed for debugging and development purposes and
 generally will be too noisy for normal program usage.
 
+### `--app-data`
+
+Overrides the normal, default location of the [[application data directory|File-Structure]]. Note
+that this option is mainly intended for usage in the official Docker image. It is not intended for
+normal use outside of that.
+
 ## Sonarr
 
 ### `--list-release-profiles`

wiki/File-Structure.md

@@ -0,0 +1,19 @@
+This page describes the general file structure used by Recyclarr for its data. Many of these are
+platform-specific.
+
+## Application Data Directory
+
+The application data directory is the root location for Recyclarr's files. With the exception of the
+main `recyclarr.yml` file, everything that Recyclarr reads or writes, by default, starts with this
+path.
+
+| Platform | Location                                  |
+| -------- | ----------------------------------------- |
+| Windows  | `%APPDATA%\recyclarr`                     |
+| Linux    | `~/.config/recyclarr`                     |
+| MacOS    | `~/Library/Application Support/recyclarr` |
+
+## Default YAML Configuration File
+
+The default YAML configuration file is `recyclarr.yml` and it is always located next to the
+Recyclarr executable.