I think a public GitHub in markdown format is a wise choice. Firstly markdown can look nice but will always be readable using cat (not what cats for but leaving

I think a public GitHub in markdown format is a wise choice. Firstly markdown can look nice but will always be readable using cat (not what cats for but leaving that to one side...), so there is the longevity factor. Using github means you’ll probably have a local copy, and you can subject the repo to your normal backup procedures. But you also have another backup in Github itself. Finally making it public will encourage you to curate it and keep it up to date and not blasé delete old stuff (and git protects you from that too because a force push is required to really delete something). Most importantly it’s easy - open any editor and start writing, then commit ‘n’ push when done.