add walkthrough video to README

README.md

@@ -19,7 +19,7 @@ Some basic knowledge of [TiddlyWiki](https://tiddlywiki.com)
 
 
 Documentation / Installation
-============================
+----------------------------
 
 Find a live version of the edition on the web with further instructions
     at https://sobjornstad.github.io/tzk/.
@@ -28,3 +28,14 @@ You can find the documentation for the CLI
      versioning with Git,
      and creating public and other derivative versions of the wiki)
     at https://tzk.readthedocs.io/en/latest/.
+
+
+Video walkthrough
+-----------------
+
+Since tzk is still in an alpha state,
+    general instructions on how to use it are somewhat lacking at the moment.
+To fill in the gap in the meantime,
+    I recorded an hour-long walkthrough showing how you might take notes using tzk;
+    you can select individual sections to watch if that's longer than you want.
+[Watch the video on YouTube](https://www.youtube.com/watch?v=9X_T-DVie8o).