Update bug report and readme for tree-sitter support.

Author: kristijanhusak

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -2,6 +2,14 @@ name: Bug report
 description: Create a report to help us improve orgmode
 labels: bug
 body:
+  - type: dropdown
+    validations:
+      required: true
+    attributes:
+      label: Are you using "tree-sitter" branch?
+      options:
+        - 'Yes'
+        - 'No'
   - type: textarea
     validations:
       required: true

README.md

@@ -14,6 +14,9 @@
 
 </div>
 
+## Tree-sitter
+Experimental tree-sitter support branch: https://github.com/kristijanhusak/orgmode.nvim/tree/tree-sitter
+
 ## Installation
 
 Use your favourite package manager: