BIRD Journey to Threads: Chapter zero of a blogpost series

[Maria Matejka]

Hello!

As we're working on multithreading support in BIRD, there is a need to 
document this. There is a user documentation (which almost doesn't 
change) and a programmer's documentation composed mostly of comments 
spread across the source code.

There is also a kind-of high-level documentation to describe how are the 
BIRD's internal processes changing. If you're just an ordinary user, you 
don't need to care much about that. We're sharing this mostly for people 
who know (or want to know) how BIRD works internally and how it is going 
to change.

The zeroth chapter is here, other chapters should follow soon:

https://en.blog.nic.cz/2021/03/15/bird-journey-to-threads-chapter-0-the-reason-why/

(Content: An introduction and summary of previous major BIRD structural 
changes.)

I deeply appreciate your feedback and questions.

Maria