improve the issue template, add a documentation feedback template

.github/ISSUE_TEMPLATE/feedback.md

@@ -0,0 +1,20 @@
+---
+name: Feedback on the documentation
+about: How can we improve the documentation?
+url: https://github.com/ueberdosis/tiptap-next/issues/new
+title: ''
+labels: documentation
+assignees: ''
+---
+
+**Which part of the documentation have you read?**
+I’ve been to the following page of the documentation …
+
+**Did you find the content helpful?**
+I think this part is really good: …
+
+**What was hard to understand, missing or misleading?**
+But you really need to improve …
+
+**What else?**
+Add any other context here.