Document how to load Images and MP3 files at run-time

doc/classes/ResourceLoader.xml

@@ -6,6 +6,7 @@
 	<description>
 		Singleton used to load resource files from the filesystem.
 		It uses the many [ResourceFormatLoader] classes registered in the engine (either built-in or from a plugin) to load files into memory and convert them to a format that can be used by the engine.
+		[b]Note:[/b] You have to import the files into the engine first to load them using [method load]. If you want to load [Image]s at run-time, you may use [method Image.load]. If you want to import audio files, you can use the snippet described in [member AudioStreamMP3.data].
 	</description>
 	<tutorials>
 		<link title="OS Test Demo">https://godotengine.org/asset-library/asset/677</link>

modules/gdscript/doc_classes/@GDScript.xml

@@ -144,6 +144,7 @@
 				[/codeblock]
 				[b]Important:[/b] The path must be absolute, a local path will just return [code]null[/code].
 				This method is a simplified version of [method ResourceLoader.load], which can be used for more advanced scenarios.
+				[b]Note:[/b] You have to import the files into the engine first to load them using [method load]. If you want to load [Image]s at run-time, you may use [method Image.load]. If you want to import audio files, you can use the snippet described in [member AudioStreamMP3.data].
 			</description>
 		</method>
 		<method name="preload">

modules/minimp3/doc_classes/AudioStreamMP3.xml

@@ -4,13 +4,36 @@
 		MP3 audio stream driver.
 	</brief_description>
 	<description>
-		MP3 audio stream driver.
+		MP3 audio stream driver. See [member data] if you want to load an MP3 file at run-time.
 	</description>
 	<tutorials>
 	</tutorials>
 	<members>
 		<member name="data" type="PackedByteArray" setter="set_data" getter="get_data" default="PackedByteArray()">
 			Contains the audio data in bytes.
+			You can load a file without having to import it beforehand using the code snippet below. Keep in mind that this snippet loads the whole file into memory and may not be ideal for huge files (hundreds of megabytes or more).
+			[codeblocks]
+			[gdscript]
+			func load_mp3(path):
+			    var file = File.new()
+			    file.open(path, File.READ)
+			    var sound = AudioStreamMP3.new()
+			    sound.data = file.get_buffer(file.get_length())
+			    file.close()
+			    return sound
+			[/gdscript]
+			[csharp]
+			public AudioStreamMP3 LoadMP3(string path)
+			{
+			    var file = new File();
+			    file.Open(path, File.READ);
+			    var sound = new AudioStreamMP3();
+			    sound.Data = file.GetBuffer(file.GetLength());
+			    file.Close();
+			    return sound;
+			}
+			[/csharp]
+			[/codeblocks]
 		</member>
 		<member name="loop" type="bool" setter="set_loop" getter="has_loop" default="false">
 			If [code]true[/code], the stream will automatically loop when it reaches the end.