You can contribute directly to the Compendium by adding a markdown file in the notes folder.
Each file begins with the date it is added, in YYYYMMDD format, followed by a dash, and is closed by the file extension, .md . (On the 28th of May 2021 this would result in a file called 20210528-Document Name.md)
Make sure to paste the metadata template at the top. If you are unsure how to tag a submission, have a look at the tags page to see which tags already exist. Tags are separated with commas and are placed between brackets.
If you prefer learning visually, you can have a look at the demonstration in the link below. (Click the image!)
If that seems too daunting, you can instead open an issue and link to a pastebin with your document in markdown formatting.