document migration format for Known

doc/migration-format.md

-# IndieHosters migration format, version 0.2.1
+# IndieHosters migration format, version 0.2.2
 
 When a user exports their data for domain.com, they get a zip or tar file that contains different files, depending on which application is
 running on their domain:
@@ -22,3 +22,12 @@ running on their domain:
 * wordpress/login.txt - username and password for the WordPress admin panel
 * wordpress/.htaccess - htaccess file for WordPress
 * wordpress/wp-content - php files to be placed in the web root
+
+## If using the 'Known' application
+
+* TLS/domain.com.pem - Concatenation of the unencrypted private and public key of the TLS certificate, and intermediate CA cert if applicable.
+* mysql/dump.sql - the dump of all their MySQL databases
+* mysql/.env - contains the MySQL password
+* known/ - php files to be placed in the web root
+* known/.env - contains the MySQL password
+* known/login.txt - email address and password for the Known admin panel