fix(docs): resolve markdownlint errors

- Fix ordered list numbering in MIGRATION.md (1,2,3 instead of 3,4,5)
- Add trailing newline to MIGRATION.md
- Add language specifier (text) to fenced code block in README.md

Co-Authored-By: Claude <noreply@anthropic.com>
Signed-off-by: Aleksei Sviridkin <f@lex.la>

charts/jellyfin/README.md

@@ -429,7 +429,8 @@ For more configuration options, see the full values documentation in [values.yam
 ### inotify Instance Limit Reached
 
 **Problem:** Jellyfin crashes with error:
-```
+
+```text
 System.IO.IOException: The configured user limit (128) on the number of inotify instances has been reached
 ```