feat: mark user editable regions in help post (#48512)

Co-authored-by: Naomi Carrigan <nhcarrigan@gmail.com>
Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>
Co-authored-by: kravmaguy <flex4lease@gmail.com>
Co-authored-by: Mrugesh Mohapatra <1884376+raisedadead@users.noreply.github.com>

Closes https://github.com/freeCodeCamp/freeCodeCamp/issues/46411

client/src/templates/Challenges/redux/create-question-epic.js

@@ -43,13 +43,36 @@ function createQuestionEpic(action$, state$, { window }) {
     ofType(actionTypes.createQuestion),
     tap(() => {
       const state = state$.value;
-      const challengeFiles = challengeFilesSelector(state);
+      let challengeFiles = challengeFilesSelector(state);
       const {
         title: challengeTitle,
         superBlock,
         block,
         helpCategory
       } = challengeMetaSelector(state);
+      if (
+        challengeFiles?.some(file => file.editableRegionBoundaries.length > 0)
+      ) {
+        const editableRegionStrings = fileExtension => {
+          const startComment = fileExtension === 'html' ? '<!--' : '/*';
+          const endComment = fileExtension === 'html' ? '-->' : '*/';
+          return `\n${startComment} User Editable Region ${endComment}\n`;
+        };
+
+        const filesWithEditableRegions = challengeFiles.map(file => {
+          const { contents, editableRegionBoundaries, ext } = file;
+          if (editableRegionBoundaries.length > 0) {
+            const comment = editableRegionStrings(ext);
+            const [start, end] = editableRegionBoundaries;
+            const lines = contents.split('\n');
+            lines.splice(start, 0, comment);
+            lines.splice(end, 0, comment);
+            return { ...file, contents: lines.join('\n') };
+          }
+          return file;
+        });
+        challengeFiles = filesWithEditableRegions;
+      }
       const {
         navigator: { userAgent },
         location: { pathname, origin }