Clean up notes folder

[firasm]

Hi @clairezxy and @TenzinJinpa2019,

Could we clean up the notes folder a little bit? Currently there exists both a .ipynb file and an .md file for most of the notes.

If you let me know which files to delete, I can do the actual deleting. Here is the tree list:

notes/
├── 01Intro.md
├── 02DataRep.ipynb
├── 02DataRep.md
├── 03Excel.md
├── 05Databases.ipynb
├── 06Python.ipynb
├── 06PythonIInotes.md
├── 07Python.ipynb
├── 09CommandLine.ipynb
├── 09CommandLine.md
├── 11Visualization.ipynb
├── 12OpenData.ipynb
├── 12OpenData.md
├── Python6.md
├── data.csv
├── input.txt
├── labs.md
├── midterm1-review.md
├── output.txt
├── part1.md
├── part2.md
├── part3.md
├── project.md
├── python-question.md
├── question.md
├── test.txt
├── test2.txt
└── visualization.md

[clairezxy]

02DataRep.md and 09CommandLine.md can be deleted as the contents are all in jupyter notebook. @firasm

[TenzinJinpa2019]

visualization.md, 06PythonIInotes.md, 12OpenData.md and Python6.md are not required as the contents are in Jupiter notebook @firasm