[vim] Add a DiagnosticFloat autocommand that shows the diagnostic window on CursorHold

Set the hold time to 300 ms.

config/nvim/lua/autocommands.lua

@@ -0,0 +1,15 @@
+-- Eryn Wells <eryn@erynwells.me>
+
+vim.opt.updatetime = 300
+
+-- Show diagnostic popup on cursor hover
+local diagnostic_float_group = vim.api.nvim_create_augroup("DiagnosticFloat", { clear = true })
+vim.api.nvim_create_autocmd("CursorHold", {
+    callback = function()
+        vim.diagnostic.open_float {
+            border = "double",
+            focusable = false,
+        }
+    end,
+    group = diagnostic_float_group,
+})