documentation about helper functions rollout seems outdated

[markwort]

Describe the bug
AFAICT, the documentation for rolling out helper functions seems to be outdated.
I expect two ways to roll out helper functions:

1. pgwatch does it on its own.
2. I run some sql scripts against a database.

Since the former only works in cases where pgwatch has a lot of privileges in the target database and this is not always compatible with security requirements, I expect that a way to use the second option exists.

However, as far as I can tell, pgwatch no longer ships the /etc/pgwatch/metrics/00_helpers/* files, which could be used to create the helpers with adequate privileges.
Yet, the documentation still mentions that this is how to roll out metrics helpers:
https://pgwat.ch/latest/tutorial/preparing_databases.html#rolling-out-common-helpers

Expected behavior

There should be a way to retrieve the definitions for helper functions in plain text SQL, so that they can be run by a user with sufficient privileges in the database-to-be-monitored, and then the pgwatch user can be granted execute privilege on the helper function.
In direct communication, @pashagolub mentioned that something like pgwatch metric "metric_name_or_preset" --init | psql -d target should already be in pgwatch, but I cannot really find if this is the case by looking at the source code quickly.
If this is the case, the documentation should be updated accordingly.

Best regards
Julian