Add more field descriptions to README.md

[vexcat]

I've been testing some guesswork on what some of the unknowns are and have found the meaning of a few more key fields!

I'll probably be submitting more push requests (or adding to this one) over the next week or so while I work on an app to display pepakura models in-browser

[phuocdh90]

Nice information! Just want to say thank you! Based on your work, I have been able to implement PDO importing for my paper craft application. I heard that you are about to create an app to display pepakura models in-browser, why not checking out mine :p

[vexcat]

That app is really well-made, good job! Is its source code available somewhere?

[phuocdh90]

Unfortunately the source code is not publicly available, since my co-author doesn’t approve of it. But if you need a feature, just request it in my Discord server (server URL is available in the app) :)

[gptlang]

@vexcat any updates on your planned app?

I'm running into issues with this script:

Traceback (most recent call last):
  File "loader.py", line 228, in <module>
    parse(data)
  File "loader.py", line 100, in parse
    print 'unk6:', arr(buf.double, buf.double, buf.double, buf.double)
  File "loader.py", line 57, in double
    return self.unpack('d')
  File "loader.py", line 27, in unpack
    ret = struct.unpack(fmt, self.read(struct.calcsize(fmt)))
struct.error: unpack requires a string argument of length 8

And can't seem to find a way around it.