docs: introduce ADR for permissionless ICS (#2001)

* init commit

* added table with keys

* show image

* nit changes

* small photo change

* small changes

* more small changes

* added note on owners

* added a negative

* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Apply suggestions from code review

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Took into account comments

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* more changes

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* nit change

* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* introducing more changes

* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* nit fixes

* nit fixes

* fixed small typo

* Update docs/docs/adrs/adr-018-permissionless-ics.md

Co-authored-by: Marius Poke <marius.poke@posteo.de>

* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* took into account comments

* nit changes

* updated table and cleared up some confusing parts

* updated diagrams

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* Update docs/docs/adrs/adr-018-permissionless-ics.md

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* updated messages

* performed more updates

* fixed typo on diagram

* small change in the diagram

* took into account comments

---------

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Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Co-authored-by: Marius Poke <marius.poke@posteo.de>