Hypelink in moveit2 tutorials

[adricort]

Hypelink from demo.launch.py stated in the moveit2 tutorials in the last pharagraph, is not working. Please update ;)

[sea-bass]

Here's the offending line, just need to remove a doc from that hyperlink:

https://github.com/moveit/moveit2_tutorials/blob/27b5ed0232cd08de9631d26e823dccc6e8766513/doc/examples/perception_pipeline/perception_pipeline_tutorial.rst?plain=1#L157