Add API doc generator, improve documentation across the board

docs/api-config.json

@@ -0,0 +1,22 @@
+{
+    "heading": "Mediabunny API reference",
+    "intro": "Here you can find detailed documentation for all classes, functions, constants and types exposed by Mediabunny's public API.",
+
+    "Samples": "Raw, unencoded chunks of media data, such as video frames or sections of audio.",
+    "Packets": "Chunks of encoded media data.",
+    "Input files & tracks": "Read input files and their tracks; demuxer API.",
+    "Input formats": "Container formats that Mediabunny can read.",
+    "Input sources": "The sources that can provide data to an `Input`.",
+    "Output files": "Create and write new media files; muxer API.",
+    "Output formats": "Container formats that Mediabunny can write.",
+    "Output targets": "The targets where `Output` writes data to.",
+    "Media sinks": "Methods for extracting media data from input files.",
+    "Media sources": "Methods for adding media data to output files.",
+    "Conversion": "A simple API for converting and transforming media files.",
+    "Codecs": "Codecs understood by Mediabunny.",
+    "Encoding": "Encoder configuration and encodability checks.",
+    "Custom coders": "API for adding custom encoders and decoders.",
+    "Miscellaneous": "Whatever's left.",
+
+    "@mediabunny/mp3-encoder": "Adds MP3 encoder support to Mediabunny."
+}