docs: Update CONTRIBUTING.md

[baNROne]

Description

• Updates the contribution guide to point to the correct path for newrelic-client-go.
• Also, generalizes the user's local path.

Type of change

• [x] Documentation

Checklist:

• [x] My commit message follows conventional commits

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 32.88%. Comparing base (92361de) to head (11461d0). Report is 17 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2664 +/- ## ========================================== + Coverage 32.82% 32.88% +0.06% ========================================== Files 98 98 Lines 26884 27091 +207 ========================================== + Hits 8824 8910 +86 - Misses 17902 18020 +118 - Partials 158 161 +3 ```

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