[KYUUBI #6068] Remove community section from user docs

# 🔍 Description
## Issue References 🔗

## Describe Your Solution 🔧

The content of the community section is a bylaw, which is settled on the website.

This PR removes it and moves the release guide into the contributing fold for the moment.

The release guide is also bylaw which is suite better in website repo.

## Types of changes 🔖

- [ ] Bugfix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)

## Test Plan 🧪

#### Behavior Without This Pull Request ⚰️

#### Behavior With This Pull Request 🎉

#### Related Unit Tests

---

# Checklist 📝

- [x] This patch was not authored or co-authored using [Generative Tooling](https://www.apache.org/legal/generative-tooling.html)

**Be nice. Be informative.**

Closes #6068 from yaooqinn/community.

Closes #6068

8e18da6 [Kent Yao] Remove community section from user docs

Authored-by: Kent Yao <[email protected]>
Signed-off-by: Cheng Pan <[email protected]>

Author: yaooqinn

CONTRIBUTING.md

@@ -61,3 +61,9 @@ TBD, please be patient for the surprise.
 ## IDE Setup Guide
 
 [IntelliJ IDEA Setup Guide](https://kyuubi.readthedocs.io/en/master/contributing/code/idea_setup.html)
+
+## Contributor Avatars
+
+<a href="https://github.com/apache/kyuubi/graphs/contributors">
+  <img src="https://contrib.rocks/image?repo=apache/kyuubi&max=1024" />
+</a>

docs/community/CONTRIBUTING.md

@@ -30,3 +30,4 @@ code to the Kyuubi project.
     debugging
     developer
     idea_setup
+    release

docs/community/collaborators.md

@@ -15,8 +15,7 @@
 - limitations under the License.
 -->
 
-Kyuubi Release Guide
-====================
+# Release Guide
 
 ## Introduction
 

docs/community/index.rst

@@ -221,12 +221,6 @@ What's Next
    contributing/code/index
    contributing/doc/index
 
-.. toctree::
-   :caption: Community
-   :maxdepth: 2
-
-   community/index
-
 .. toctree::
    :caption: Appendix
    :maxdepth: 2