Mention pagination flag for classroom cli student repo downloads (#27597)

Co-authored-by: Sophie <29382425+sophietheking@users.noreply.github.com>

Author: bertheyman

content/education/manage-coursework-with-github-classroom/teach-with-github-classroom/using-github-classroom-with-github-cli.md

@@ -103,3 +103,5 @@ gh classroom clone student-repos
 ```
 
 Clones student repositories from a given assignment. By default, the student repos are cloned into the current directory a directory named after the assignment slug. To clone into a different directory, use the `--directory` flag. If the directory does not exists, it will be created.
+
+By default, results are paginated by 30. To get a different number of repositories, use the `--per-page NUMBER` flag.