Update troubleshooting.md

[mulles]

corrected gstream install command for linux.

[patrickelectric]

Hi @mulles, thank you very much for your contribution!
Are you using which version of ubuntu ?
apt should work fine, can you explain why this change is necessary ?

[mulles]

TL, DR: No need to correct anything, my fault.

Please excuse, I was not aware that ubuntu 16.04 and above, have a tool available called "apt". And that apt is the new package manager.
Thus all fine.

I leave this as reference for further explanation should somebody with older ubuntu version encounter this issue:
"Apt was introduced in 16.04 to simplify the package manager and to merge multiple commands into one single command. The functions from “apt-get” have been taken and have been created to function in similar ways in Apt."
-https://www.maketecheasier.com/apt-vs-apt-get-ubuntu/

[patrickelectric]

Np, be free to send any PR that you find relevant ;)
Can we close this PR ?

[mulles]

Sure, will close.
Its a pleasure engaging with you and the rest of Blue robotics Team.

[patrickelectric]

@mulles be free to chat with us in gitter: https://gitter.im/bluerobotics/ardusub
See you around !