Update docs to note bumped git version requirements

doc/install/requirements.md

@@ -67,6 +67,11 @@ The minimum required Go version is 1.13.
 
 ### Git versions
 
+From GitLab 13.11:
+
+- Git 2.31.x and later is required. We recommend you use the
+  [Git version provided by Gitaly](installation.md#git).
+
 From GitLab 13.6:
 
 - Git 2.29.x and later is required.

doc/update/index.md

@@ -352,6 +352,11 @@ NOTE:
 Specific information that follow related to Ruby and Git versions do not apply to [Omnibus installations](https://docs.gitlab.com/omnibus/)
 and [Helm Chart deployments](https://docs.gitlab.com/charts/). They come with appropriate Ruby and Git versions and are not using system binaries for Ruby and Git. There is no need to install Ruby or Git when utilizing these two approaches.
 
+### 13.11.0
+
+Git 2.31.x and later is required. We recommend you use the
+[Git version provided by Gitaly](../install/installation.md#git).
+
 ### 13.6.0
 
 Ruby 2.7.2 is required. GitLab will not start with Ruby 2.6.6 or older versions.