Fix parity testing broken link (#1471)

Author: HarshCasper

layouts/partials/coverage/coverage_details.html

@@ -16,7 +16,7 @@ <h3 id="howtoread">How to read the test details?</h3>
             <li>information about validation:</li>
             <ul>
                 <li><span class="coverage-report-tag-aws-validated">AWS validated</span> the test is validated against AWS, meaning it run successfully against real AWS as well</li>
-                <li><span class="coverage-report-tag-snapshot">Snapshot Tested</span> this is a <a href="/contributing/parity-testing/">snapshot parity test</a>, meaning the responses are validated against AWS</li>
+                <li><span class="coverage-report-tag-snapshot">Snapshot Tested</span> this is a <a href="https://github.com/localstack/localstack/blob/master/docs/testing/parity-testing/README.md">snapshot parity test</a>, meaning the responses are validated against AWS</li>
             </ul>
         </ul>
 </ul>

layouts/partials/coverage/coverage_table.html

@@ -34,6 +34,6 @@ <h3 id="terminology">Terminology</h3>
     {{ end }}
     <li><b>Terraform Validated:</b> operation tested with <a href="/user-guide/integrations/terraform/">Terraform</a></li>
     <li><b>AWS Validated:</b> the integration test that includes this operation call was validated against AWS</li>
-    <li><b>Snapshot Tested:</b> the operation is part of a <a href="/contributing/parity-testing/">snapshot parity test</a>, which verifies the responses by LocalStack and AWS are the same</li>
+    <li><b>Snapshot Tested:</b> the operation is part of a <a href="https://github.com/localstack/localstack/blob/master/docs/testing/parity-testing/README.md">snapshot parity test</a>, which verifies the responses by LocalStack and AWS are the same</li>
     </ul>
 </div>