nvim: init: Enable closeoff and linematch options for diffopt

linematch option got merged a few hours ago with this commit.
https://github.com/neovim/neovim/pull/14537

While at it, set closeoff as well.

nvim/.config/nvim/init.lua

@@ -28,7 +28,7 @@ vim.o.writebackup    = false
 vim.o.swapfile       = false
 vim.o.sessionoptions = 'buffers,curdir,tabpages,winsize'
 vim.o.shada          = ''
-vim.o.diffopt        = 'filler,internal,algorithm:histogram,indent-heuristic'
+vim.o.diffopt        = 'filler,internal,algorithm:histogram,indent-heuristic,closeoff,linematch:60'
 vim.o.scrolloff      = 999
 vim.o.formatoptions  = "crqn1j"
 vim.o.signcolumn     = "auto:1-2"