Fix documentation is deprecated error

[digitalfrost]

Fixes:

[nvim-cmp] documentation is deprecated.
[nvim-cmp] Please use window.documentation = cmp.config.window.bordered() instead.

Also fixes snippets not working and error:

Error executing vim.schedule lua callback: ...te/pack/packer/start/nvim-cmp/lua/cmp/view/docs_view.lua:38: bad argument #1 to 'min' (number expected, got nil)
stack traceback:
        [C]: in function 'min'
        ...te/pack/packer/start/nvim-cmp/lua/cmp/view/docs_view.lua:38: in function 'open'
        ...re/nvim/site/pack/packer/start/nvim-cmp/lua/cmp/view.lua:238: in function 'callback'
        .../site/pack/packer/start/nvim-cmp/lua/cmp/utils/async.lua:95: in function 'cb'
        vim/_editor.lua:256: in function <vim/_editor.lua:256>

[digitalfrost]

Duplicates #201 Fixes #158

[korniychuk]

There is no border field in the window we have to use window.documentation.border

[gnmearacaun]

fixed by #231

[d13g0]

shouldn't this fix be propagated to "subsequent" branches?