Mention bundle resources in the resource manual

Fixes #420

docs/en/manuals/project-settings.md

@@ -38,7 +38,7 @@ A list of URLs to the project *Library URL*s. Refer to the [Libraries manual](/m
 
 #### Custom Resources
 `custom_resources`
-A comma separated list of resources that will be included in the project. If directories are specified, all files and directories in that directory are recursively included. The resources can be loaded using [`sys.load_resource()`](/ref/sys/#sys.load_resource).
+A comma separated list of resources that will be included in the project. If directories are specified, all files and directories in that directory are recursively included. The resources can be loaded using [`sys.load_resource()`](/ref/sys/#sys.load_resource). Loading custom resources is covered in more detail in the [File Access manual](/manuals/file-access/#how-to-access-files-bundled-with-the-application).
 
 #### Bundle Resources
 `bundle_resources`
@@ -49,7 +49,7 @@ Supported platforms are `ios`, `android`, `osx`, `win32`, `linux`, `web`, `switc
 A subfolder named `common` is also allowed, containing resource files common for all platforms.
 
 Access to files within the the bundle resources is platform specific. The Lua module `io` is one way to do it. Care must be taken to have the correct file paths for the platform.
-(e.g. prefix using "file:///android_asset/" on Android)
+(e.g. prefix using "file:///android_asset/" on Android). Loading files is covered in more detail in the [File Access manual](/manuals/file-access/#how-to-access-files-bundled-with-the-application).
 
 #### Bundle Exclude Resources
 `bundle_exclude_resources`

docs/en/manuals/resource.md

@@ -14,10 +14,14 @@ When you build a game in Defold, you statically declare the resource tree. Every
 - Game object and component data (atlases, sounds etc).
 - Factory component prototypes (game objects and collections).
 - Collection proxy component references (collections).
-- Custom resources declared in *game.project*.
+- [Custom resources](/manuals/project-settings/#custom-resources) declared in *game.project*.
 
 ![Resource tree](images/resource/resource_tree.png)
 
+::: sidenote
+Defold also has a concept of [bundle resources](/manuals/project-settings/#bundle-resources). Bundle resources are included with the application bundle, but are not part of the resource tree. The bundle resources can be anything from platform specific support files to external files [loaded from the file system](/manuals/file-access/#how-to-access-files-bundled-with-the-application) and used by your game. One such examples is FMOD sound banks.
+:::
+
 When the game is *bundled*, only what is in the resource tree will be included. Anything that is not referenced in the tree is left out. There is no need to manually select what to include or exclude from the bundle.
 
 When the game is *run*, the engine starts at the bootstrap root of the tree and pulls resources into memory: