Update README.md
Add links for XCK
@@ -39,6 +39,7 @@ ACH is under active development but already in production for multiple companies
| SHR | Shared Network Entry | [Link](test/ach-shr-read/main.go) | [Link](test/ach-shr-write/main.go) |
| TEL | Telephone-Initiated Entry | [Link](test/ach-tel-read/main.go) | [Link](test/ach-tel-write/main.go) |
| WEB | Internet-initiated Entries | [Link](test/ach-web-read/main.go) | [Link](test/ach-web-write/main.go) |
+| XCK | Destroyed Check Entry | [Link](test/ach-xck-read/main.go) | [Link](test/ach-xck-write/main.go) |
</details>
