Update README with Page up/down keys

README.md

@@ -50,11 +50,13 @@ It will be much faster the next time as it no longer needs to fetch the entire r
 
 After some time you will see something like this:
 
-![Screenshot of redu showing the contents of a repo with some marks active](screenshot.jpg)
+![Screenshot of redu showing the contents of a repo with some marks active](screenshot.png)
 
-You can navigate using **hjkl** or the **arrow keys**.
+You can navigate using the **arrow keys** or **hjkl**.
 Going right enters a directory and going left leaves back to the parent.
 
+**PgUp**/**PgDown** or **C-b**/**C-b** scroll up or down a full page.
+
 The size that redu shows for each item is the maximum size of the item
 across all snapshots. That is, it's the size of that item for the snapshot
 where it is the biggest.