add items to troubleshooting section

[buedaswag]

1. student is installing the requirements, but there is no requirements file

2. student is pulling the ds-prep-course repo, but the pull fails because of uncommitted local changes

[buedaswag]

this needs to go here as well

[buedaswag]

[buedaswag]

number 1 above is solved by number 2 so i didn't include it

[buedaswag]

what should students do when they encounter this situation?

[Juliana-R]

Is this resolved? @buedaswag If yes please close, if not please create actionable.