update CONTRIBUTING.md file to remove GitHub mirror reference

Change-Id: I658e70b7071acd5139e0b1ff7ae0e84317acfb5e
1 file changed
tree: 050f582e330f89565d59c60beb5d3bc2c85edd56
  1. plugin/
  2. src/
  3. .gitignore
  4. CONTRIBUTING.md
  5. LICENSE
  6. NOTICE