fix(docs): quote requirement specifiers to prevent shell redirection

Co-Authored-By: Claude <claude@anthropic.com>
Signed-off-by: Rohan Devasthale <rdevasth@redhat.com>

Author: rd4398

docs/how-tos/multiple-version-bootstrap.rst

@@ -38,10 +38,10 @@ Pass ``--multiple-versions`` to either ``bootstrap`` or
 .. code-block:: bash
 
    # Serial bootstrap
-   fromager bootstrap --multiple-versions requests>=2.28
+   fromager bootstrap --multiple-versions 'requests>=2.28'
 
    # Parallel bootstrap
-   fromager bootstrap-parallel --multiple-versions requests>=2.28
+   fromager bootstrap-parallel --multiple-versions 'requests>=2.28'
 
 This resolves every version of ``requests`` that satisfies ``>=2.28`` and
 bootstraps each one.