docs chunks versioning via git branches

[gotoplanb]

thinking something like have each chunk/example in markdown like:

100_intro.md
200_middle.md
300_end.md

then use Bash and cat to compile a full document. For inserting new pieces, you'd use something like 110_thing.md to insert into a section into the first chapter. Then 111_chunk.md to be the first chunk/example.

Still thinking about how to have versioning of an example for Express 3 and Express 4 for example. Or Django 1.4 vs 1.7. Perhaps each markdown chunk needs some hash so we could compare chunk between versions even if the files have changed for sequence.

Alternatively we could have all filenames be hashed like fjalsdf521.md then use some key/value to both sequence the chunk and give a name/value to the markdown chunk.