"just need to update it a bit"
If your own site is outdated, I would advise you to contribute to an existing site or service, since receiving traffic requires that the site be kept up to date, otherwise you will fall from ranking in search engines, the "freshness" of the page / site.
As soon as someone else deletes the text of the textbook that will eventually happen, it will have a higher search result than your site if they just make changes on the main page more often than you do.
Another thing you could do is write an e-book or iBook, as the content is harder to clear and you donβt need to create a whole site.
JBRWilkinson
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