Where is wordlist file stored

I would like to manually add words to the learned word list but I cannot find the file.

I have found the file in "home/don/.local/share/onboard/models"

It is the "en_US.lm" file but I am not sure how to edit it.

Changes I make there does not seem to change the word suggestions. I would like to be able to include strings such as email addresses.

Right now I use the snippets for strings like emails.