Swag dbip: Add example for blacklisting a continent

[TheMihle]

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• I have read the contributing guideline and understand that I have made the correct modifications

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Description:

Adds template lines/example of blacklisting one or more continents

Benefits of this PR and context:

Easier for users to setup for people that want to blacklist a continent as a whole rather than or in addition to individual countries.

How Has This Been Tested?

Had the SWAG docker with the docker mod installed on my unraid NAS. Tested with the changes in the config files directly there with proxy for Nextcloud. Worked as I expected there.

Source / References:

[Roxedus]

Is there a good, documented list of the continent codes, like there are with country codes? (i realize its only 7)

[TheMihle]

Is there a good, documented list of the continent codes, like there are with country codes? (i realize its only 7)

I just used this and tested it would be the same, it is for Africa and South America at least:
https://support.maxmind.com/hc/en-us/articles/4414877149467-IP-Geolocation-Data#h_01FRRJSP2B14KSWWJTXKRWZGKJ

And there is this from DBIP site:
https://db-ip.com/db/format/ip-to-country/csv.html

3 continent
Two-letter continent code [AF, AS, EU, NA, OC, SA, AN]

Could add a link, or just list them without a link as a comment?

[LinuxServer-CI]

PR build pushed to ghcr.io/linuxserver/mods:pull_request_1055

[TheMihle]

btw, the same thing may work in the Maxmind mod but I have not tested it so I dont feel like making a PR for that one at the moment