chore(config): add meaningful example strings

config.example.toml

@@ -4,13 +4,13 @@
 # slow. Consider exporting your key to a file and providing it below.
 # Note that providing an ID or file on the command-line will override either in
 # the config.
-signing_key_id = ''
+signing_key_id = 'ABCDEF012345679CAFEBABE0DECAFC0FFEEBAD11'
 
 # The PGP secret key file to use for signing - this will use sequoia and is
 # orders of magnitude faster than using gpg-agent.
 # Note that providing an ID or file on the command-line will override either in
 # the config.
-signing_key_file = ''
+signing_key_file = '/path/to/secret-key.pgp'
 
 # The number of threads to use. 0 for system's amount of logical cores
 threads = 0