kijiproject.github.com: DOCS-147. Add instructions for using paste mode in the express shell.

issue: https://jira.kiji.org/browse/DOCS-147
review: https://review.kiji.org/r/1482
commit: https://github.com/kijiproject/kijiproject.github.com/commit/b982e9c8a0d7d89ecf8d15e95d0e12cb81513743