minor #20982 Mention the community review guide (ogizanagi)

This PR was merged into the 2.7 branch.

Discussion
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Mention the community review guide

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | N/A
| License       | MIT
| Doc PR        | N/A

I think it's a good idea to reference this guide on the repository main page and contributing guide. Especially as it explains processes for reviewing that are specific to Symfony (Carson Bot).

Commits
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313defa Mention the community review guide

Author: fabpot

CONTRIBUTING.md

@@ -5,6 +5,7 @@ Symfony is an open source, community-driven project.
 
 If you'd like to contribute, please read the following documents:
 
+* [Reviewing issues/pull requests][0]
 * [Reporting a Bug][1]
 * [Submitting a Patch][2]
 * [Symfony Core Team][3]
@@ -14,6 +15,7 @@ If you'd like to contribute, please read the following documents:
 * [Coding Standards][7]
 * [Conventions][8]
 
+[0]: https://symfony.com/doc/current/contributing/community/reviews.html
 [1]: https://symfony.com/doc/current/contributing/code/bugs.html
 [2]: https://symfony.com/doc/current/contributing/code/patches.html
 [3]: https://symfony.com/doc/current/contributing/code/core_team.html

README.md

@@ -41,6 +41,14 @@ please read the [Contributing Code][3] part of the documentation. If you're subm
 a pull request, please follow the guidelines in the [Submitting a Patch][4] section
 and use [Pull Request Template][5].
 
+Community Reviews
+-----------------
+
+If you don't feel ready to contribute code or patches, reviewing issues and pull 
+requests can be a great start to get involved and give back. In fact, people who 
+"triage" issues are the backbone to Symfony's success!  
+More information can be found in the [Community Reviews][8] guide.
+
 Running Symfony Tests
 ----------------------
 
@@ -54,3 +62,4 @@ Information on how to run the Symfony test suite can be found in the
 [5]: https://symfony.com/doc/current/contributing/code/patches.html#make-a-pull-request
 [6]: https://symfony.com/doc/master/contributing/code/tests.html
 [7]: https://symfony.com/doc/current/book/installation.html#installing-the-symfony-installer
+[8]: https://symfony.com/doc/current/contributing/community/reviews.html