add stats api docs

mkdocs/docs/api/stats.md

@@ -0,0 +1,37 @@
+# Statistics API endpoints
+
+## Primary
+
+⚠️ **Experimental**
+
+**GET** `/api/stats/primary/`
+
+Get primary statistics for your videos, channels, playlists and download queue.
+
+## Watch Progress
+
+⚠️ **Experimental**
+
+**GET** `/api/stats/watch/`
+
+Get statistics over your watch progress.
+
+## Download History
+
+⚠️ **Experimental**
+
+**GET** `/api/stats/downloadhist/`
+
+Get statistics for last days download history.
+
+## Biggest Channels
+
+⚠️ **Experimental**
+
+**GET** `/api/stats/biggestchannels/`
+
+Get a list of biggest channels, specify *order* parameter.
+
+Parameter:  
+
+- order: doc_count (default), duration, media_size

mkdocs/mkdocs.yml

@@ -36,6 +36,7 @@ nav:
         - 'Download': 'api/download.md'
         - 'Snapshot': 'api/snapshot.md'
         - 'Task': 'api/task.md'
+        - 'Stats': 'api/stats.md'
         - 'Additional': 'api/additional.md'
     - Links:
         - 'Main site': https://www.tubearchivist.com