Add tag for search engine to skip old tutorial pages in search

[auman66]

Description

Overview of your issue here.

Your environment

• ROS Distro: [Indigo|Jade|Kinetic]
• OS Version: e.g. Ubuntu 16.04
• Source or Binary build?
• If binary, which release version?
• If source, which git commit or tag?

Steps to reproduce

Tell us how to reproduce this issue. Attempt to provide a working demo, perhaps using Docker.

Expected behaviour

Tell us what should happen

Backtrace or Console output

Use gist.github.com to copy-paste the console output or segfault backtrace using gdb.

[welcome]

Thanks for reporting an issue. Because we're a volunteer community, providing a pull request with suggested changes is always welcomed.