Add log_cleared to the common index (#2400)

### What
Help users discover the `log_cleared` API by adding it to the index.

Resolves:
 - #2348

TODO:
- [ ] After merging, this change should be cherry-picked into
`release-0.6` branch and documentation should be re-deployed.

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [ ] I've included a screenshot or gif (if applicable)

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rerun_py/docs/gen_common_index.py

@@ -122,6 +122,11 @@ class Section:
         # "LogLevel", "LoggingHandler"
         func_list=["log_text_entry"],
     ),
+    Section(
+        title="Clearing Entities",
+        module_summary=None,
+        func_list=["log_cleared"],
+    ),
     Section(
         title="Helpers",
         module_summary="script_helpers",