Add crosslinks to troubleshooting (#2428)

* Add crosslinks to troubleshooting

* Remove excess slashes

* Change link text

Author: theletterf

docs/reference/index.md

@@ -32,3 +32,6 @@ More detailed information on how the Agent works can be found in the [advanced t
 
 APM Agents work in conjunction with the [APM Server](docs-content://solutions/observability/apm/index.md), [Elasticsearch](docs-content://get-started/introduction.md#what-is-es), and [Kibana](docs-content://get-started/introduction.md#what-is-kib). The [APM documentation](docs-content://solutions/observability/apm/index.md) provides details on how these components work together, and provides a matrix outlining [Agent and Server compatibility](docs-content://solutions/observability/apm/apm-agent-compatibility.md).
 
+## Troubleshooting
+
+If you're experiencing issues with the APM Python agent, refer to [Troubleshoot APM Python Agent](docs-content://troubleshoot/observability/apm-agent-python/apm-python-agent.md).

docs/reference/toc.yml

@@ -30,4 +30,6 @@ toc:
     children:
       - file: upgrading-6-x.md
       - file: upgrading-5-x.md
-      - file: upgrading-4-x.md
+      - file: upgrading-4-x.md
+  - title: Troubleshooting
+    crosslink: docs-content://troubleshoot/observability/apm-agent-python/apm-python-agent.md