How to contribute
The most useful contribution, other than bugfixes, is translations.
If you speak a language other than English, and are familiar with common equivalents to TRUE/FALSE or yes/no, submit those equivalents! The really easy way is to open a GitHub issue with your translations - the more complicated way is forking the package, taking a look at the categorical_booleans structure, adding your translations to that, and submitting a pull request.
As examples of the idiomatic usage we see, current english-language values are, for TRUE:
y
yes
t
true
1
And for FALSE:
n
no
f
false
0
none
The idiomatic bit is key; if you see something commonly in survey data, whether it's precisely equivalent to "true" linguistically or not is moot - we'd like to have it.
All contributors get listed in the DESCRIPTION file; additionally, the first few will (if they want) get free stickers, which is nice.