nvim: Add workaround for completion-nvim bug

completion-nvim chaining seems to not allow multiple `triggered_only`
definitions in the same linked chain of various completion options. In
other words, when in pandoc files there is no possibility to have
completion for lsp and buffer words by default and for paths on pressing
`/`, as well as bib-citekeys on pressing `@`.

Doing so requires automatically switching sources, which in turn is of
little use when writing pandoc normally and it hangs every couple of
seconds to recompile the bibtex list as soon as it runs out of buffer
words to complete.

Ideally, the completion-nvim bug should be looked at, but also the
bibtex completion possibly completely turned into a lua parsed
completer, so it does not depend on `vim-pandoc` and its (presumably)
slower vimscript implementation.

nvim/.config/nvim/spell/en.utf-8.add

@@ -67,3 +67,5 @@ glyphosate
 Monstanto
 univseralism
 universalisms
+CSO
+dialogue