Since lei is for personal mailboxes, I don't think lei needs to
keep keyword and label changes in history. And fix a minor
wording problem ("or" => "nor") while we're at it.
Debian 8.x (jessie) users, use Debian 8.5 or later if using Xapian:
https://bugs.debian.org/808610
-public-inbox will never store unregeneratable data in Xapian
-or any other search database we might use; Xapian corruption
-will not destroy critical data.
+public-inbox-* commands will never store unregeneratable data in
+Xapian nor any other search database we might use; Xapian
+corruption will not destroy critical data. Note: `lei' DOES store
+unregeneratable data in Xapian and SQLite.
See the public-inbox-overview(7) man page for the next steps once
the installation is complete.