Readme: add some email-contact obfuscation

[rubo77]

No description provided.

[jplitza]

We already have instructions how to remove the owner information if desired. Obfuscating them is strictly inferior to removing them (do you really think bots don't recognize (a), (at), and all the other replacements?). Furthermore, your command does the replacement in all parts of the JSON, which is nuts. For example, node names should not be touched by such a measure.

[rubo77]

nodenames are not allowed an @ sign, and removing the information is not an option for us, we want open contacts, so obfuscation is the least we can do, maybe it will stom 50% of the spam-bots

[rubo77]

Actually, instead of closing this issue, I was sure, the pro's will come up with better suggestions, how to find a better solution (than just replacing @ with (a) ). That's, why I started this PR.

There should be a solution suggested in the README, because just publish all user emails plain in nodes.json is not a good practise. while broadcasting a contact information itself is a good thing.

Maybe we suggest to strip emails from the contact field here?

[rubo77]

I edited the regex, so it only matches the contact and replaces @ with at. and added the hint

Be crative with the replacement rule or strip emails completely.