feat(git): Add .gitattributes for ansible-vault git diff

Signed-off-by: Tuan-Dat Tran <tuan-dat.tran@tudattr.dev>

README.md

@@ -66,6 +66,17 @@ The following roles are defined:
     ansible-playbook -i vars/k3s.ini playbooks/kubernetes_setup.yml
     ```
 
+## Notes
+
+### Vault Git Diff
+
+This repo has a `.gitattributes` which points at the repos ansible-vault files.
+These can be temporarily decrypted for git diff by adding this in conjunction with the `.gitattributes`:
+```sh
+# https://stackoverflow.com/questions/29937195/how-to-diff-ansible-vault-changes
+git config --global diff.ansible-vault.textconv "ansible-vault view"
+```
+
 ## Disclaimer
 
 This project is highly customized for the author's specific environment. Using it without modification is not recommended.