Add to Glossary

Go to the "Glossary acronyms" in the left navigation, then edit page using 'edit source'.

Once there you can add a new line of content in the format:

;ABBR:full text of abbreviation

so it looks like this

or

After that, any time the abbreviation is used on another page, it will automatically be applied with the full description as a hover link.

This will take half an hour or so to actually show up as it seems to search the pages and remember things!