[CHANGE] Add the possibility to add entries to Boltdb

[steffenfritz]

admftrove should have an option to add entries easily from a text file, one hash per line, to an existing database.

[steffenfritz]

This is already possible. If there is already a nsrl.db file in the directory, you can add additional entries by copying amdftrove into the db directory and execute it with the --creatensrl flag and a source file. This will not override the database but add all new hashes to it.

--> Update documentation

[steffenfritz]

Documentation updated: https://filetrove.fritz.wtf/docs/example/