Improve pretty-printing for text-only nodes

luamml-xmlwriter.lua

@@ -34,6 +34,10 @@ local function write_elem(tree, indent)
     return out .. '/>'
   end
   out = out .. '>'
+  -- Never indent the content if it's purely text.
+  if #tree == 1 and type(tree[1]) == 'string' then
+    indent = nil
+  end
   local inner_indent = indent and indent .. '  '
   local is_string
   for _, elem in ipairs(tree) do