add a combined plot

Author: miku

Slides.md

@@ -62,15 +62,6 @@ $ git shortlog -s -n | wc -l
 From a [git-of-theseus](https://github.com/erikbern/git-of-theseus) analysis
 (as of 0a1a092c4b56a1d4033372fbd07924dad8cbb50b):
 
-Authors (top 20 plus others).
-
-![](static/theseus/authors_norm.png)
-
-Code age over time.
-
-![](static/theseus/cohorts_norm.png)
-
-Extensions.
-
-![](static/theseus/exts_norm.png)
+Authors (top 20 plus others); code age; extensions.
 
+![Various plots generated with git-of-theseus](static/theseus/stats_combined.png)