Remove unnecessary --recursive option to git clone (#48379)

From installing / Running from source.
Since the repomerge, Ansible doesn't use submodules. Also, between 2.12.0 and 2.13.0 git dropped '--recursive' in favor of '--recurse-submodules'.

docs/docsite/rst/installation_guide/intro_installation.rst

@@ -339,7 +339,7 @@ To install from source, clone the Ansible git repository:
 
 .. code-block:: bash
 
-    $ git clone https://github.com/ansible/ansible.git --recursive
+    $ git clone https://github.com/ansible/ansible.git
     $ cd ./ansible
 
 Once git has cloned the Ansible repository, setup the Ansible environment: