Formally define the goals of Codex

I think we should have some agreed upon document (even just as part of the README) directly stating which characters are or are not in scope for inclusion in this project, and how simple should a given character be to access.

This would also include some guiding principle for assigning names to characters, such as when abbreviations are okay and when they aren't, when can a character be accessible through multiple distinct names (and whether one of them should be considered "canonical"?), whether we strive to describe the usage of characters, their origin/formal meaning, or their visual appearance (or rather when do we do which).

In my opinion this will greatly help prioritise new additions to the repo and help reviewers to decide what changes to approve

(side note: do we have a preference for how to stylise the name; e.g. codex, Codex, or CodeX?)

Start by reviewing the README and the issue discussion to identify any existing statements about Codex's scope, character accessibility, naming, aliases, and descriptions. The work is done when the project has an agreed, maintainable document covering those goals and the preferred styling of the project name.