docs: note that gevent instrumentation is automatic in table (#8819)

We had conflicting info between our advanced usage on gevent and this
table. Although it might be a bit debatable I think that we can say it's
automatic in most cases and therefore can switch this to yes.

## Checklist

- [x] Change(s) are motivated and described in the PR description
- [x] Testing strategy is described if automated tests are not included
in the PR
- [x] Risks are described (performance impact, potential for breakage,
maintainability)
- [x] Change is maintainable (easy to change, telemetry, documentation)
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed or label `changelog/no-changelog` is set
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/))
- [x] Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))
- [x] If this PR changes the public interface, I've notified
`@DataDog/apm-tees`.
- [x] If change touches code that signs or publishes builds or packages,
or handles credentials of any kind, I've requested a review from
`@DataDog/security-design-and-guidance`.

## Reviewer Checklist

- [ ] Title is accurate
- [ ] All changes are related to the pull request's stated goal
- [ ] Description motivates each change
- [ ] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- [ ] Testing strategy adequately addresses listed risks
- [ ] Change is maintainable (easy to change, telemetry, documentation)
- [ ] Release note makes sense to a user of the library
- [ ] Author has acknowledged and discussed the performance implications
of this PR as reported in the benchmarks PR comment
- [ ] Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

Author: ZStriker19

docs/index.rst

@@ -90,7 +90,7 @@ contacting support.
 +--------------------------------------------------+---------------+----------------+
 | :ref:`flask_login`                               | >= 0.6.2      | Yes [6]_       |
 +--------------------------------------------------+---------------+----------------+
-| :ref:`gevent` (greenlet>=1.0)                    | >= 20.12      | No             |
+| :ref:`gevent` (greenlet>=1.0)                    | >= 20.12      | Yes            |
 +--------------------------------------------------+---------------+----------------+
 | :ref:`grpc`                                      | >= 1.34       | Yes [5]_       |
 +--------------------------------------------------+---------------+----------------+