Add release note for customized memory and cpu resources feature

Change-Id: I667b6e1737b5c001e6a13914bab725d1c7094fde
Story: 2001586
Task: 14367

releasenotes/notes/resources-customized-5f5382d40e375dc1.yaml

@@ -0,0 +1,10 @@
+---
+prelude: >
+    Support customizing resource limitation for functions, both cpu and memory
+    are supported.
+features:
+  - |
+    Support customizing memory and cpu resource limitation for functions. The
+    user can specify ``memory_size`` and ``cpu`` when creating functions,
+    otherwise the default values are used. Refer to Qinling documentation for
+    more details.