Missing documentation about the include directive for requirements files (#20090)

* Missing documentation about the include directive for requirements files

* Code block needs blank line

* Correct casing

docs/docsite/rst/galaxy.rst

@@ -134,6 +134,38 @@ Use the following example as a guide for specifying roles in *requirements.yml*:
       scm: git
       version: "0.1"  # quoted, so YAML doesn't parse this as a floating-point value
 
+Installing multiple roles from multiple files
+=============================================
+
+At a basic level, including requirements files allows you to break up bits of roles into smaller files. Role includes pull in roles from other files.
+
+Use the following command to install roles includes in *requirements.yml*  + *webserver,yml*
+
+::
+
+    ansible-galaxy install -r requirements.yml
+
+Content of the *requirements.yml* file:
+
+::
+
+    # from galaxy
+    - src: yatesr.timezone
+
+    - include: <path_to_requirements>/webserver.yml
+
+
+Content of the *webserver.yml* file:
+
+::
+
+    # from github
+    - src: https://github.com/bennojoy/nginx
+
+    # from Bitbucket
+    - src: git+http://bitbucket.org/willthames/git-ansible-galaxy
+      version: v1.4
+
 Dependencies
 ============