Add case studies

[yurishkuro]

The home page has a section "Organizations using OpenTracing". It would be great if some of the links pointed to blog posts with case studies, like a couple of paragraphs of why the given org chose to use OT, in which language, with which frameworks.

[saloni-garg]

@yurishkuro, I'll work on this issue. Would it be great to have a Google Doc for now, where I'll jot down all the case studies, and then we can insert them in the website?

[yurishkuro]

We worked with CNCF marketing team to do case studies for Jaeger (not published yet), but those were more like full length blog posts based on interviews. Not sure if they did something similar for OpenTracing.

In order to grow this Case Studies page someone needs to do these mini-interviews with the companies using it.