[BUG] Issue link in Contributing.md is invalid

[avishnu]

What happened:
The link is throwing up a 404 error.

What you expected to happen:

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:

Environment:

• OpenYurt version:
• Kubernetes version (use kubectl version):
• OS (e.g: cat /etc/os-release):
• Kernel (e.g. uname -a):
• Install tools:
• Others:

others

/kind bug