Putting the /jetstream folder within /deep-dives since that's where it lives in the sidebar
The jetstream sidebar was manually created, so there was a missing file that wasn't previously being shown in the sidebar: deep-dives/jetstream/adding-a-platform
Made the jetstream folder autogenerated
Added sidebar_position to each of the docs to mimic the current order
Before vs after:
![image](https://github.com/mozilla/experimenter-docs/assets/43795363/b949d021-7627-4433-8ee2-013ebea85528)