Create and complet instructions on CMS Open Data

[caredg]

Should probably be based on https://cms-opendata-workshop.github.io/workshop-lesson-dataset-scouting/

[katilp]

I added some text in https://cms-opendata-guide.web.cern.ch/tools/cmsopendata/, I did not check this first so it is actually not what you intended. Thinking about it, "CODP" and "CMS Open data" do not really fit under "Computing tools". We should probably have a separate section, and an additional "Finding data" based on the data scouting lesson:

│
├── CMS Open data
│      ├── About CMS Open data
│      ├── CERN Open data portal
│      ├── Finding data
├── Computing tools
        ├── Unix...
        ├── Root

I'm not sure what the current "CMS Twiki" is meant to contain. The twiki pages are briefly mentioned already in https://cms-opendata-guide.web.cern.ch/#the-sites-philosophy

[jieunyoo]

I restructured the pages as requested on Dec. 10th. I am leaving this issue open since it includes a reference link for the "Finding data" page.