chore(common): add documentation issue template (#223)

Author: soonum

.github/ISSUE_TEMPLATE/documentation-issue.md

@@ -0,0 +1,27 @@
+---
+name: Documentation Issue
+about: Fill any issue related to product documentation
+title: 'docs(<category>): short description'
+labels: documentation
+assignees: ''
+
+---
+
+### Category  
+<!-- Check the category and replace the placeholder <category> in the title accordingly-->
+
+- [x] **docs(user)** — user-facing content: guides, tutorials, concept explanations, etc.  
+- [ ] **docs(api)** — interfaces: contracts, SDKs, plugin APIs, etc.  
+- [ ] **docs(code)** — code examples, templates, scripts, tests, etc.  
+- [ ] **docs(misc)** — structure, navigation, styling, feedback, housekeeping, etc.  
+
+### Context / Background  
+<!-- Describe the issue and provide related contexts.-->
+
+### Target Files/Pages  
+<!-- Link or describe the relevant doc files or sections to be updated/created.  -->
+
+### Tasks  
+- [ ] Task 1  
+- [ ] Task 2  
+- [ ] Task 3