Not OP, but I've been keeping a "journal" repo for the last 4 months. There's a single dev.md file in there, where I separate each entry with "---". Whenever I encounter an issue or learn something new, I document it for later reference.

It honestly depends on what it is - sometimes in the repository, for a wiki it’s stored in the wiki itself, otherwise it might be as simple as a text file in a web directory.

I do same and keep everything in Evernote organized in subfolders and tagged. Quick to find and helps 100% when it's time to rebuild/setup a server.