add git-yodel

after/plugin/git-yodel.lua

@@ -0,0 +1,12 @@
+local status_ok, yodel = pcall(require, "git-yodel")
+if not status_ok then
+	return
+end
+
+yodel.setup {
+  diffpreview = {
+    border = 'shadow',
+    width = 'auto',
+    height = 'auto',
+  }
+}