Add README files 2/8 (#5766)

* add 5 README files

* empty commit to (hopefully) get rid of the `test-are-failling` label

* Update ciphers/README.md

Co-authored-by: John Law <[email protected]>

* Update conversions/README.md

Co-authored-by: John Law <[email protected]>

* Update cellular_automata/README.md

Co-authored-by: John Law <[email protected]>

* Update computer_vision/README.md

Co-authored-by: John Law <[email protected]>

* Update conversions/README.md

Co-authored-by: John Law <[email protected]>

* Update compression/README.md

Co-authored-by: John Law <[email protected]>