pip: add an example of an offline installation (#54327)

* pip: add an example of an offline installation

* remove whitespaces from blank lines

lib/ansible/modules/packaging/language/pip.py

@@ -190,6 +190,11 @@ EXAMPLES = '''
     requirements: /my_app/requirements.txt
     extra_args: -i https://example.com/pypi/simple
 
+# Install specified python requirements offline from a local directory with downloaded packages.
+- pip:
+    requirements: /my_app/requirements.txt
+    extra_args: "--no-index --find-links=file:///my_downloaded_packages_dir"
+
 # Install (Bottle) for Python 3.3 specifically,using the 'pip-3.3' executable.
 - pip:
     name: bottle