added unfold as standard to TeX specific nvim settings

neovim/.config/nvim/ftplugin/tex.vim

@@ -4,3 +4,4 @@ setlocal spelllang=de
 setlocal foldmethod=expr
 setlocal foldexpr=vimtex#fold#level(v:lnum)
 setlocal foldtext=vimtex#fold#text()
+setlocal foldlevel=99