Add list of apps that use djinni

[jothepro]

As a project maintainer I'd like to promote djinni as "not yet dead" and "more popular than you might think" in this repository, to attract new users & contributors. To do so, I'd like to add a section like "These companies rely on djinni" or "these apps rely on djinni" to the README.
This will help us as a community to have a higher chance to thrive in the long term.

TODO:

• collect an initial list of apps/developers using djinni that are willing to be promoted on our repo (doesn't matter if they already use our repo in the first place)
  • ask @a4z & @bojanin if their companies would be willing to be listed
  • I am planning to publish an app, but it's a toy project and will probably take a while to go public... :P
  • contact Dave Hagedorn if he'd like TextNow to be listed. (thanks to @a4z for sharing this podcast)
• decide if and how the collected information should be presented (list of companies vs list of explicit apps)
• prepare a first version of the listing

[jothepro]

@a4z @bojanin this idea came to my mind yesterday while I was listening to the podcast shared by @a4z. Feel free to tell me what you think about it :)

[a4z]

This is very much related to cross-language-cpp/djinni#11
and I agree that making some advertising for this project should be done.

[jothepro]

@bojanin in cross-language-cpp/djinni#11 you mentioned that you/your company would be willing to appear in the list of apps that use djinni. Is there any news? Just comment the information in this issue if you like, then I'll try to figure out how to best present it. :)