Closes #36 update readme

[kaz462]

Thank you for your Pull Request! We have developed this task checklist from the Development Process Guide to help with the final steps of the process. Completing the below tasks helps to ensure our reviewers can maximize their time on your code as well as making sure the admiral codebase remains robust and consistent.

Please check off each taskbox as an acknowledgment that you completed the task or check off that it is not relevant to your Pull Request. This checklist is part of the Github Action workflows and the Pull Request will not be merged into the devel branch until you have checked off each task.

• Place Closes #<insert_issue_number> into the beginning of your Pull Request Title (Use Edit button in top-right if you need to update)
• Code is formatted according to the tidyverse style guide. Run styler::style_file() to style R and Rmd files
• Updated relevant unit tests or have written new unit tests, which should consider realistic data scenarios and edge cases, e.g. empty datasets, errors, boundary cases etc. - See Unit Test Guide
• If you removed/replaced any function and/or function parameters, did you fully follow the deprecation guidance?
• Update to all relevant roxygen headers and examples, including keywords and families. Refer to the categorization of functions to tag appropriate keyword/family.
• Run devtools::document() so all .Rd files in the man folder and the NAMESPACE file in the project root are updated appropriately
• Address any updates needed for vignettes and/or templates
• Update NEWS.md if the changes pertain to a user-facing function (i.e. it has an @export tag) or documentation aimed at users (rather than developers)
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[kaz462]

• README is updated based on the most recent folder structure and naming conventions discussions

• For CODEOWNERS, will create a full list and update it another time Full list of CODEOWNERS #43

[manciniedoardo]

lgtm, just a few final minor points

[kaz462]

@manciniedoardo @bundfussr Thanks for the review!