added link to supplementary lecture

covers material mentioned on "extra" slides from the last official course lecture

Author: jeremymanning

README.md

@@ -114,4 +114,5 @@ Note: Only assignments marked *active* are guarantee to be in their final form--
 - Required readings: [Manning (2021)](https://www.dropbox.com/s/7873vuevillrbze/mann21.pdf), [Manning (2020)](https://www.dropbox.com/s/pzj7nr6ma4rlosd/context_chapter.pdf), [Baldassano et al. (2017)](https://www.dropbox.com/s/ytjokm6fnocj9ut/BaldEtal17.pdf)
 - [**Lecture 25 recording**](https://youtu.be/yXElJRBdhYc): multi-timescale models, scale invariance, time cells, temporal receptive windows, concluding thoughts [[PDF](https://github.com/ContextLab/human-memory/raw/main/slides/lecture_25.pdf)][[KEY](https://github.com/ContextLab/human-memory/raw/main/slides/lecture_25.key)]
   - Extra slides (not covered in class): [[PDF](https://github.com/ContextLab/human-memory/raw/main/slides/lecture_25_extras.pdf)][[KEY](https://github.com/ContextLab/human-memory/raw/main/slides/lecture_25_extras.key)]
+  - [**Supplementary lecture that covers material mentioned on extra slides**](https://www.youtube.com/watch?v=yUCxk7sFny8) (source: talk given at Berkeley in 2020): thought spaces, thought trajectories, multi-timescale models and their neural correlates, geometric models of memory, where we "go" when we remember, modeling classroom learning, AI teachers, models of conversation
 - Assignments: [Problem set 7](https://github.com/ContextLab/human-memory/raw/main/problem%20sets/current%20year/problem%20set%207/problem%20set%207.pdf), [Final exam](https://canvas.dartmouth.edu/courses/45671/discussion_topics/317828)