update readme for v2.9.0

Author: alicebob

README.md

@@ -18,13 +18,15 @@ There are no dependencies on external binaries, so you can easily integrate it i
 
 ## Changelog
 
-### v2.8.0
+### v2.9.0
 
-Proper `v2` in go.mod.
+- proper versioned import of github.com/gomodule/redigo (thanks @yfei1)
+- fix messages generated by PSUBSCRIBE
+- optional internal seed (thanks @zikaeroh)
 
-### v2.7.0
+### v2.8.0
 
-SWAPDB
+Proper `v2` in go.mod.
 
 ### older