Document minimum neovim requirement in regard to vim.diagnostic #71
Description
#70 (4073f76) introduced the use of vim.diagnostic.severity.ERROR, etc. in lua/lsp-status/diagnostics.lua, but this is available only in neovim 0.6.0+. This means that this plugin is NOT compatible with neovim 0.5.1 or below any more. Please document this change somewhere in the README if you would like to keep the minimum compatible version as neovim 0.6.0. For example, up to which version(commit) this plugin will be compatible with (such as e8e5303, which is the parent of 4073f76).
In my opinion, it'd be good to support a bit older version (0.5.1) for the time being by removing thee use of constants.