The man page mentions the "Personal dictionary file" ... https://manpages.ubuntu.com/manpages/trusty/en/man4/hunspell.4.html
Personal dictionaries are simple word lists. Asterisk at the first character position signs prohibition. A second word separated by a slash sets the affixation.
If I can include those words in the main Dictionary file, why would anyone use personal file? Is any language using this?