doc: Add redirect for GUI issues and pull requests

Author: MarcoFalke

.github/ISSUE_TEMPLATE.md

@@ -4,7 +4,11 @@ General bitcoin questions and/or support requests are best directed to the Bitco
 
 For reporting security issues, please read instructions at https://bitcoincore.org/en/contact/.
 
-If the node is "stuck" during sync or giving "block checksum mismatch" errors, please ensure your hardware is stable by running memtest and observe CPU temperature with a load-test tool such as linpack before creating an issue! -->
+If the node is "stuck" during sync or giving "block checksum mismatch" errors, please ensure your hardware is stable by running memtest and observe CPU temperature with a load-test tool such as linpack before creating an issue!
+
+Any report, issue or feature request related to the GUI should be reported at
+https://github.com/bitcoin-core/gui/issues/
+-->
 
 <!-- Describe the issue -->
 <!--- What behavior did you expect? -->

.github/ISSUE_TEMPLATE/gui_issue.md

@@ -0,0 +1,11 @@
+---
+name: An issue or feature request related to the GUI
+about: Any report, issue or feature request related to the GUI should be reported at https://github.com/bitcoin-core/gui/issues/
+title: Any report, issue or feature request related to the GUI should be reported at https://github.com/bitcoin-core/gui/issues/
+labels: GUI
+assignees: ''
+
+---
+
+Any report, issue or feature request related to the GUI should be reported at
+https://github.com/bitcoin-core/gui/issues/

.github/PULL_REQUEST_TEMPLATE.md

@@ -3,6 +3,10 @@
 
 Pull requests without a rationale and clear improvement may be closed
 immediately.
+
+GUI-related pull requests should be opened against
+https://github.com/bitcoin-core/gui
+first. See CONTRIBUTING.md
 -->
 
 <!--