[KYUUBI #5602] Improve issue template for 2023 Kyuubi Code Contributi…

…on Program

### _Why are the changes needed?_

- Add the link of [2023 Kyuubi Code Contribution Program](#5357)
- Fix typos
- Add task level dropdown

### _How was this patch tested?_
- [ ] Add some test cases that check the changes thoroughly including negative and positive cases if possible

- [x] Add screenshots for manual tests if appropriate

Reviewers can preview it at https://github.com/pan3793/test/issues/new/choose

<img width="1004" alt="image" src="https://github.com/apache/kyuubi/assets/26535726/29bd9dab-528c-4982-947d-a406db412a43">

- [ ] [Run test](https://kyuubi.readthedocs.io/en/master/contributing/code/testing.html#running-tests) locally before make a pull request

### _Was this patch authored or co-authored using generative AI tooling?_

No

Closes #5602 from pan3793/template.

Closes #5602

c71c4b9 [Cheng Pan] typo
1f29eaa [Cheng Pan] fix
fba5cd2 [Cheng Pan] nit
a1485fc [Cheng Pan] Improve issue template for 2023 Kyuubi Code Contribution Program

Authored-by: Cheng Pan <[email protected]>
Signed-off-by: Cheng Pan <[email protected]>

.github/ISSUE_TEMPLATE/code-contrib-task.yml

@@ -41,6 +41,19 @@ body:
           have good logical thinking and the ability to solve complex problems, be proficient in programming
           skills or algorithms
 
+  - type: dropdown
+    id: level
+    attributes:
+      label: What's the level of this task?
+      multiple: false
+      options:
+        - TRIVIAL
+        - EASY
+        - MEDIUM
+        - CHALLENGE
+    validations:
+      required: true
+
   - type: checkboxes
     attributes:
       label: Code of Conduct
@@ -65,19 +78,19 @@ body:
       description: Mentor is required for MEDIUM and CHALLENGE tasks, to guide contributors to complete the task.
       options:
         - label: >
-            I have sufficient knowledge and experience of this task, and I volunteer to be the mentor of this task
-            to guide contributors to complete the task.
+            I have sufficient expertise on this task, and I volunteer to be a mentor of this task to guide
+            contributors through the task.
           required: false
 
   - type: textarea
     attributes:
       label: Skill requirements
-      description: Which stills are required for contributors who want to take this task?
+      description: What skills are required for contributors who want to take this task?
       placeholder: |
         e.g.
-        - Basic knowledge on Scala Programing Language
+        - Basic knowledge on Scala programming language
         - Familiar with Apache Maven, Docker and GitHub Action
-        - Basic knowledge on network programing and Apache Thrift RPC framework
+        - Basic knowledge on network programming and Apache Thrift RPC framework
         - Familiar with Apache Spark
         - ...
     validations:
@@ -105,8 +118,9 @@ body:
   - type: textarea
     attributes:
       label: Additional context
-      placeholder: >
-        Anything else that related to this task that the contributors need to know.
+      description: Anything else that related to this task that the contributors need to know.
+      value: |
+        Introduction of [2023 Kyuubi Code Contribution Program](https://github.com/apache/kyuubi/issues/5357)
     validations:
       required: false