Update changelog-seen in config.toml.example

This got out of sync when the version was bumped last time.

Long-term we may want to find an easier way to maintain this that
doesn't require bumping the version in three different places. Off the
top of my head I can't think of anything, though.

config.toml.example

@@ -13,7 +13,7 @@
 # If it does not match the version that is currently running,
 # `x.py` will prompt you to update it and read the changelog.
 # See `src/bootstrap/CHANGELOG.md` for more information.
-changelog-seen = 1
+changelog-seen = 2
 
 # =============================================================================
 # Global Settings