'What is D-Bus' introductory document

[Lawrence D'Oliveiro]

One thing I had forgotten, is I had written up just such a D-Bus
introduction myself, some years ago. It’s included in the README for
DBussy <https://github.com/ldo/dbussy>, as the sections entitled “What
Is D-Bus?” and “Standard Interfaces”. Together, they sum up everything
I consider important to know about D-Bus, in just under a thousand
words: that it is high-level, message-based, has an extensive but not
extensible type system, and so on.