nvim: add C lsp 'clangd'

stow/.config/nvim/lua/nico/lazy/lsp.lua

@@ -34,6 +34,7 @@ return {
             python = { "pyright" },
             rust = { "nil" },
             go = { "gopls" },
+            c = { "clangd" },
           },
           prefer_local = true, -- Prefer locally installed servers over nix-shell
           -- Default config passed to all servers to specify on_attach callback and other options.