docs: remove Go modules vendor reference

Signed-off-by: Caleb Cartwright <caleb.cartwright@outlook.com>

CONTRIBUTING.md

@@ -107,17 +107,6 @@ git commit --amend --no-edit --signoff
 git push --force-with-lease <remote-name> <branch-name>
 ```
 
-### Use of Third-party code
-
-- All third-party code must be placed in the `vendor/` folder.
-- `vendor/` folder is managed by Go modules and stores the source code of third-party Go dependencies. - The `vendor/` folder should not be modified manually.
-- Third-party code must include licenses.
-
-A non-exclusive list of code that must be places in `vendor/`:
-
-- Open source, free software, or commercially-licensed code.
-- Tools or libraries or protocols that are open source, free software, or commercially licensed.
-
 **Thank You!** - Your contributions to open source, large or small, make projects like this possible. Thank you for taking the time to contribute.
 
 ### Fork and set upstream