Support embedding parts of a roc-file with the static-site-gen platform about roc

[Anton-4]

Hmm, the addition of snippet does make it clear we're not referring to a function named hello.
It also seems like the cost of verbosity is quite low, it's not like with a variable name for example.
I'd like to try it out with snippet for now.

[isaacvando]

Could the syntax for referencing a snippet be file:main.roc:hello instead?

[michaelkpfeifer]

The Roc formatter replaces

### start snippet hello

by

# ## start snipped hello

which means that every file using this feature is formatted incorrectly. (Compare failed test run https://github.com/roc-lang/roc/actions/runs/7562066467/job/20699431954.)

Assuming that there are good reasons why the Roc formatter replaces ### by # ## (and #-- by # --) , a simple way to solve this is to use ## instead of ### . But this will probably lead to other problems since ## seems to be used for documentation purposes.

I feel that # ## is not ideal since people would probably wonder why there is an additional space character. Maybe # -- ?