Add API documentation

docs/API.md

@@ -0,0 +1,44 @@
+# API
+
+NewLeaf reimplements the Invidious API and is compatible with it.
+
+[→ See the Invidious API documentation](https://github.com/iv-org/documentation/blob/master/API.md)
+
+## NewLeaf
+
+These endpoints are implemented:
+
+- `/api/v1/videos/{id}`
+- `/api/v1/channels/{ucid}`
+- `/api/v1/channels/{ucid}/{part}`
+- `/api/v1/channels/{part}/{ucid}`
+- `/api/v1/search?q={search}`
+- `/api/v1/search/suggestions?q={search}`
+- `/vi/{id}/{file}`
+- `/api/manifest/dash/id/{id}`
+
+These endpoints are somewhat implemented:
+
+- `/api/v1/captions/{id}` - no auto-captions
+
+These endpoints are not implemented yet, but will be in the future:
+
+- `/api/v1/channels/{ucid}/playlists`
+- `/api/v1/channels/playlists/{ucid}`
+- `/api/v1/channels/search/{ucid}`
+- `/api/v1/playlists/{plid}`
+- `/api/v1/mixes/{rdid}`
+- `/api/v1/comments/{id}`
+
+These endpoints must be discussed:
+
+- `/api/v1/stats`
+- `/api/v1/annotations/{id}`
+- `/api/v1/trending`
+- `/api/v1/top`
+- `/api/v1/popular`
+- `/api/v1/channels/{ucid}/comments`
+
+These endpoints will not be implemented:
+
+- `/api/v1/insights/{id}` - because YouTube removed insights.