Change numbering of sHoTT files

[jonweinb]

I think as a leftover from some older way of organizing the numbering of the files in the sHoTT directory starts at 03. This should really be 01. The file names and all references in the .md files should be changed accordingly.

[emilyriehl]

Fine with me.

[emilyriehl]

The original file numbering pairs with the sections of the RS paper. But this makes less sense now that we're adding in stuff from your paper. So I agree that we should just simplify and start numbering from 1 (or 0 to be consistent with the HoTT files).

[jonweinb]

Oh of course, I completely forgot about that even being the reason...
I'm fine with either starting at 0 or 1.

[fizruk]

I suggest to wait for imports to appear in rzk (see rzk-lang/rzk#71).
Then we won't have to use numbers in the filenames and have more flexible organisation of files overall.

[jonweinb]

Great idea, thanks!