chore: fix docs builds by re-adding eleventy and ignoring gitignore again (#5240)

Author: JoshuaKGoldberg

.eleventy.js

@@ -46,6 +46,8 @@ module.exports = function (eleventyConfig) {
 
   eleventyConfig.setLibrary('md', markdown);
 
+  eleventyConfig.setUseGitIgnore(false);
+
   return {
     passthroughFileCopy: true,
     dir: {